TexasKayakFisherman.com

Reference
http://diablopaddlesports.com/store?cat=boats

In the market for a kayak I can stand up in for river fly fishing and taking it to the Texas coast for going after Reds. I already have a Pescador Pro 10 and an Old Town Vapor 10 Kayak (which I mainly use for bringing a buddy along or fishing with my Dad as it's more stable and he's older) and will likely sell my Pescador to help fund the upgrade.
Looking for input around the 12 ft Adios (69lbs) vs the 10 ft Chupacabra (56lbs). I'm not a big guy (5' 9" 170 lbs) so I normally prefer smaller kayaks for ease of transport and maneuverability (I have a truck bed to transport them, so no vehicle transport concerns). I'm really just concerned about tracking and maneuverability of each model. I can probably get the Chupacabra to do what I need, but I've just seen some vids/images of how stable the Adios is and just think that if I'm going to spend the money, I might as well get something I could pretty much dance on if I wanted to (though standing on an ice chest looking for reds is a more likely use case). As a side note, as someone who lives in Austin, I like the idea that it's a local company with a good reputation.
Anyone have any experiences with either or both of these?

no direct experience for you, except a little river paddling in a demo.
My understanding is to track in coast wind, you definitely want a skeg addition on either of these boats (holds true for any boat that sits you behind center).
You'll also want your seat position low to paddle at the coast.
What I did note in the river, the pull cord made these easy to stand, and the stability is good.

I demo'd an Amigo for a day. I really liked it although the demo boat didn't have the skeg added. The stability was incredible and I might give it a very slight edge over the Jackson Mayfly in stability. I probably would have bought a Diablo if ACK was having their sale and demo days in my time frame. By the time I equipped it equally to the standard Mayfly, it would have cost more money. Plus the Mayfly is designed specifically for fly fishing and has almost no snag points for stripping line. I have not yet snagged on anything in the boat other than my big feet. I just had my Mayfly on the San Juan River in NM for a week and I couldn't be happier with it.

As far as the Chupacabra, the thought of something brittle does not appeal to me. Maybe I'm too rough on them but I have accidentally dropped mine a few feet a couple times while loading / unloading.

If weight is not an issue, get the adios. A little more stable, tracks better. Both will accomplish what you want to accomplish though. On either boat, get the skeg.

more to add - there was a KT Diaries episode floating the Devil's R. in the Diablo close to when the boat was introduced.
It was obviously a stable platform for fly fishing.

Thanks on the replies everyone. Austin Kayak let's you rent yaks for a day for like $30 so I may try one or both of these yaks out.

that demo on the San Marcos river (TG), my buddy brought home a Coosa for a river boat, but I liked the Diablo better, and it's certainly a Lot more wind-slick.