Lightweight thru-hiking shoes

You might try one of the other Merrel Barefoot shoes. The Sonic Glove looks a bit tougher and the Embark Glove is lined with Gore-Tex. Although I'm not sure you'd want something waterproof in the AT? Also Innov-8 has some great minimalist trail shoes that look like they could take a real beating.

"Is there better/lighter/more durable options out there so I won't have to replace these every 300-500 miles "
I replaced my shoes every 500-600 miles and in most cases they needed it bad. I would be careful trying to get the last mile out of any shoe. I hiked with a guy that had over 1000 miles on a pair of New Balance. They catastrophically destructed and he was forced to wasted half a day getting in new pair in Seattle. Also, shoes can show no outward sign of wear but can be structurally shot causing harm to your feet.

Shoes are going to be a very personal thing and what works for you could be a disaster for me. I used four pairs of LaSportiva Wildcats on my PCT thru. The two size 12's were great but the two size 12.5 had the outside mesh just shred go figure. I also saw many pairs of Salomon xp pro ultras get holes on the sides of the shoe. It happened on the one pair I wore on the trip as well. If I were hiking again I would seriously consider Brooks Cascadias. They got rave reviews from owner I talked with.

Take care of your feet, you don't want them mad at you.

It might be worth waiting til January to check out the new New Balance MT110s. A couple previews:

http://www.irunfar.com/2011/08/new-balance-mt110-preview-2.html

http://bikernate.blogspot.com/2011/08/shoe-review-new-balance-mt110.html

In the comments on the irunfar article Anton Krupicka mentions that he's put 500 miles on a pair with zero breakdown in the upper. They're pretty inexpensive and should be widely available if/when replacement is needed.

I love my Inov-8 295s. Light, fast drying, good sticky sole, a little cushion. Everyone I know who tries these loves them. I had to buy off Zappos, but I am sold on them now.

Do not cheap out on your shoes. Shoe life isn't limited to 3-500 miles because they'll fall apart, no, they're limited to that mileage because the EVA midsole wears out. When it wears out you may suffer from overpronation because the wedge has compressed into the midsole, you may have atrocious stability because your heel is falling off the edges of the now-hardened and flattened midsole, instead of minimal or zero heel lift you may suffer from negative heel lift because the EVA in the heel is flattened, you may suffer from plantar fascia pain because the compressed EVA midsole cannot do its job of cushioning any more, etc.

So let's say you really want to push the shoe until it falls apart. In effect you're saying that you don't care about cushioning, so get a shoe that literally doesn't have cushioning (no midsole) or get a shoe that has a PU midsole. Inov-8 just announced a shoe that doesn't have a midsole, so that shoe doesn't have the 3-500 mile limitation that every other shoe with an EVA midsole has. You can wear that midsole-less shoe until it falls apart. I personally wouldn't use that shoe for a thru hike because I know bruising to my feet will quickly take me off the trail. A shoe with a PU midsole will last a lot longer, but doesn't provide as much cushioning, and I don't know of any lightweight shoes that have one.

"I love my Inov-8 295s. "

Do you get more than 300-500 miles with them (requirement from the original poster)? I ask this since I've been really disappointed how fast X-Talon 212 gets in bad condition (that eva midsole got flat:( ).

Don't know how long my new Columbia Drainmakers will last, but they are cheap, light, the soles are great on wet rocks and the shoes dry faster than X-Talons. They are quite soft but do have some raise on the heel so they might not be what the OP was looking for.

Like the others have commented you will want to replace your shoes in that 300-500 mile range. Personally I like to replace them as close to 400 miles as I can. Some shoes will last longer – others sometimes shorter – but I know what walking on bottomed out shoes for 150 miles in PA felt like and will never do it again.

I'd also recommend something that isn't a barefoot shoe. I run in the trail gloves and I think their great but for a long hike I go back to shoes I know will forgive me heel striking late in the day. I've also found that the lightest shoes aren't necessarily the best shoes. When I'm planning a thru hike I want a pair of shoes I can walk 30+ miles every day in comfortably and most 'minimalist' shoes do not fill this bill – for me personally again. I'd recommend looking into Inov-8 or La Sportiva. They're typically the more expensive shoe but having hiked in many other brands they're shoes reek of higher quality.

Let me correct my previous post somewhat. Inov-8 already has a shoe without a midsole that also has an outsole with aggressive lugs. The bad part is that shoe is made on their performance last that many hikers find to be too narrow. The shoe I was thinking about is called the Bare-X 180 that also doesn't have an EVA midsole and is built upon their anatomical last that is wider, but it's a road shoe without the big lugs that you'll probably want on the trail. In any case, if you go without a midsole, you'll want something with a stiffer outsole or a good rockplate so that you don't bruise the soles of your feet or break the bones in your feet. I'd also suggest giving yourself over a year to train with shoes like this since an injury can take a full year for the tissues to fully heal, nevermind full recuperation…and you don't want to hit the trail with a pre-existing injury.

I thur hiked the AT last year, hiked in Vibram five fingers,

I currently wear a pair of the Merrel Tough Gloves everyday.

They offer more protection then the five fingers and if you want to go the minimal route would be a fine option. They do not have large lugs for alot of traction but if ya take your time, use hiking poles, carry a light load you should be fine and not fall much.

My suggestion is bringing a second pair of footwear(crocs would work) to wear in town. You will have sore feet but the only time it was unbearable was on pavement or other man made surfaces. I made the mistake of not having a second pair of shoes and being stubborn even after realizing the issue. I used the NB MT100 for a hundred miles in the beginning alternating in bad weather with the more minimal five fingers, they shredded after a hundred miles (mesh sides), not sure if the NB MT110 solved this issue or not.

Like others have said train with minimal shoes now. Walking is different then running in minimal shoes (running is easier, more fluid)

Goodluck