Cascadia 6s

if you are using them for trail running the 7's are defintely better than the 6's. they hug your feet better and are not as "sloppy" when running technical trails.

if you are using them for hiking only, I don't think it makes much difference. the shoes are basically the same, only the 7's lacing changed a bit to keep them a bit snugger on your feet when moving fast.

I know the rage is to go to less and less drop, but heel toe drop is a personal preference in my opinion. Go with what feels right for you.

I got a free pair of Cascadia 6s a while back through a friend that's a race director.
Not really my type of shoe, but as the Pure Grits were just out, Brooks didn't want to give any away. So I gave the 6s a try.

I think they're absolute pigs, especially for running anything rocky, slippery, or technical. On one of my first runs I was slipping and tripping all over the place; they're just too tall and stiff, making them what I believe to be a broken ankle waiting to happen. The ground feel in them is terrible. I was having trouble running/balancing on wet logs, river rocks, etc.

I've kept them for yardwork and for around the house; I think they would probably be OK for walking/backpacking on packed trails. I've considered them for long distances…but anything outside of that and they just feel way too clumsy for me.

These will be used for 3-4 hiking trips in the Appalachian Mountains with a 20-25 lbs. pack

I won't be using these for running.

agreed that the Cascadia is a pretty poor "technical" running shoe, where precision and control matter.

it has, however, been one of the most popular 100 mile shoes over the last several years, where long slow mileage tends to make one want a bit of protection.
it excels on fire road type situations.

I can't vouch for how good/poor the Cascadias are for trailrunning, but I will put in my positive opinion of them as great trail shoes. I have hiked with the Cascadia 5's and 6's the last few years of doing the JMT and they work great for my wide foot. FWIW I carry about 21 – 23 lbs fully loaded for 5 days, and put in anywhere from 22 – 30 miles per day with the Cascadias and they have held up well. I have tried on the 7's and they feel nice, I just haven't picked them up yet for a fair evaluation of them. I may have to get a pair with my REI dividend and give them a shot.

I would highly suggest the 7's instead, much better control and they feel much better in your feet. And FWIW, I think that the 7's probably breath better than the 6's.