I realized I never really followed up with how I liked the truck, and I hate finding threads about issues I'm having only to have no conclusions or just 'got it working, thanks!'. Here are my feelings about this truck after 2 (short) trips and (almost) 3 months of ownership. I'm also going to start a build thread at some point, now that I have something built up. Some spoilers below.
Overall, I love the truck. The package from AEV is a really great value and having it all crash tested and OEM was what pushed me over the edge for the Bison. Out of the box (before any modification) road handling is amazing. Even with the AT tires and off-roady suspension it easily handles the best of any truck I test drove (Ram was a close second). Very little nose dive on hard braking, corners great. A little bit of cabin noise from the tires but quieter than my '04 CRV. I took her out on the Tail of the Dragon and it did beautifly, sure it's not a Golf, but it wasn't bad!
Gas milage has been fantastic, easily better than GM's EPA test shows. On a 1500 mile trip to TN (Cherokee NF, near Cherohala Skyway) I got about 21.5 MPG over the entire trip, about 2/3 highway miles 1/3 mountain roads and a tiny bit of gravel. I've gotten 23ish MPG on 'around town' highways that don't exceed 65. Better than I could have hoped for. Be aware I drive this thing like an old man, which probably helps, and constantly speeding passed cars is a huge hit to MPG.
Here is how she sits now, and this is how I daily drive it (the bike rack isn't on all the time, but the RTT likely will be):
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Don't want to get into the specifics of the build BUT I will say that even with the RTT and rack, city MPG was mostly unaffected (maybe 0.5 MPG less?) but over 70 MPH it gets between 18 and 20 depending on the terrain. It's maybe a tiny bit rougher on bumps but handling is otherwise unaffected or minorly affected.
I am also personally a fan of the interior, although this is highly subjective. It's simple, the placement of stuff makes sense, and it's very comfy.
It's not all great, there are obviously a few things that I don't like. It's mostly minor nitpicking, but they're also very frustrating because these are basically just laziness on GM's part. Biggest thing is headlights suck. I knew this going in, and my expectations were so low that I actually found them serviceable for city driving etc. If you live in the country, you might upgrade to LED bulbs. My plan for this truck is 'as stock as reasonably achievable' so I'm just leaving it and will add aux lights soon. There are also no predrilled roof rack holes (Tacoma has them but many don't). This truck (and all Colorados?) used to come with full length breathers on front and rear axle, transmission, transfer case, but it seems like in '19 or '20 they went to shorter ones. Not a huge deal, but it's a step backwards (If you're in Asia, they might still come with full length ones). There are a few other minor downsides (they have downgraded the brake slightly, but it's still g2g for GVWR) to the '21. Finally, for the price, the warranty is kind of on the low side, 5 years/60k miles. Many competitors are 100k (or lifetime).
Also, one of the things I ended up having to trade off was the level 2 self driving (only Toyota offers this on their OR trims, and only with a factory 1" lift). So far, I don't regret my choice, this car is already way less stressful to drive than my old CRV (combination of cabin noise, Android Auto, and comfort).