You're gonna get a lot of folks telling you to search for this topic.
However, I'll offer up my limited experience with the CZ shadow. I just got one from AA as I'm making the switch from a Glock 34.
I've borrowed a friends CZC. So, over the last couple of days I've compared them against each other.
Ok, they do feel different but they also have different triggers. Since I'm new to CZ's I can't think of which models are which. The non-technical terms would be the one from CZC has the most curved trigger and the AA has the trigger with less curvature. The AA pulls less on the trigger gauge (I tested them last night) and it's also smoother to me. The CZC is slightly more crisp on SA pull but only barely. Again to me. You gotta realize that all parts are different and in combination with another part can make for a different feel for each different gun. So, I believe it's all to be taken with a grain of salt.
Now, I'll say this, I met the guys from AA when picking mine up. I've also talked with them several times over the last several weeks during the whole process. And I've been pleased with thier service! I spent some time with Matt this last weekend and he's a freakin bad mofo when it comes shooting, he is also a cool guy! Extremely informative and answered all my questions, and I asked a lot! They will go the extra mile to take care of you. I have no doubt!
I'm sure CZC and CGW would also take care of you too! I've actually talked with them all via email and AA, CGW over the phone. I've never been able to get CZC on the phone.
As as for doing it yourself,..... Do you have the right tools? Do you know what to do? I'd be leery of someone who's not renowned for doing this work to offer up instruction. Take the wrong angle off and yup you've ruined a part at the very least. So, ask is your time and any hair pulling worth it the money you'd spend on the labor(still gotta buy parts). I say hair because I've wanted to pull mine out before from getting into something I wasn't equipped to take on. Though I'm bald so,..... I just end up scraping my scalp.
One last thing, which is gonna be easier to resale? One built buy a pro like AA or one that's been bubba'd? Any potential buyer is gonna wonder if it's gonna function and if it's gonna go full auto! At least I would!
Good luck!