Searching for a WPB Jacket

The Arc'teryx Alpha SL pullover meets your criteria (weight is close) and is a solid option. The OR Paladin in 3 layer Pertex, but a bit heavier. Patagonia also has numerous options which fudge on one criteria or another.

Backcountry.com is having a sale on a lot of rain and technical shells that may bring some of the $350+ items within your budget.

Still for what you're looking for most all shells will come in around the 12-13oz mark with pitzips. 10oz without. Basically of the three constraints of 10oz, 3L, and pit zips there is no solution I know of, it's pick two, and usually at the $300+ price point.

I have an REI Kimtah eVent parka. No pit zips but it doesn't seem to need them. Even the retail price was decent and if you're a member just wait for a 20% discount in the mail as I did.

In the past I've had pit zips sewn into four different jackts and parkas. It's possible I would do the same with my Kimtah but not likely, given its breathability.

The Zpacks Breathable Waterproof jacket meets my criteria at under 5 oz.

I'm considering it. It's just kind of ugly.

I got a Zpacks one recently. It definitely meets your criteria and its definitely ugly. The torso length is longer than most jackets which is good for coverage and I really like the hood design

Felt like it breathed better than a 2.5 layer jacket I had but not as good as a gore active shell. That was some real subjective around the house testing with zippers closed.

Packs up a bit smaller than the active shell too, which is nice.

While it may technically have 3 layers the Zpacks is not the same construction as a typical 3L wpb. Traditional 3Ls have a face fabric, a wpb membrane, and finally a protective lining. 2.5 layers have the lining coated with plastic dots to provide abrasion resistance (at expense of breathability).

The wpb cuben laminate has a face fabric, a reinforcing layer of dyneema, and then a wpb membrane made of ePTFE if I remember correctly. That was I think the first wpb fabric that cubic tech made and I'm not sure if they changed the design much for the fabric used by zpacks. If it is an unlined ePTFE than it will be quite breathable but prone to clogging by dirt and have durability issues without a liner fabric. I still here it's a great jacket but just be forewarned that it may not be a true 3L construction in the traditional sense.

Dustin may well be right about the way the layers are made up and the potential durability issues – I have no idea. All I can offer is that it definitely feels better against the skin than a 2.5 layer jacket.

"I have an REI Kimtah eVent parka. No pit zips but it doesn't seem to need them."

That has been my experience with a WestComb event jacket I got last year. ON my old gortex jacket most of the time I opened the pit zips. with Events higher breathability most of the time you probably will not need pit zips.

Unfortunately the lightest Event jackets are about 10oz without pit zips.

How about the new Patagonia M10?

It's on their homepage right now.

Only downside I can see is that it is marked at $370 and REI doesn't carry it (can't get sale price).

My Patagonia Super Cell is great. Found it for $150, and it's a GoreTex jacket at 13oz with pit zips and a fantastic hood.