Thanks, everyone for your opinions. Basically everyone here is saying what I think and I go back in forth between "run now!" and "this could work out!"

On the same day I rode the stock-Onix and the Trek for about 30 minutes each. I knew that as-was the Onix wasn't for me, and the Trek felt fantastic. This same-day riding was when I decided perceived value in the frame was the same, but component-wise the Onix had an advantage I could appreciate. I've also ridden both models on different days, but definitely overall spent more time on the Trek than the bike I eventually bought (I know, shoot me now).

indysteel, the new handlebars definitely brought in the reach (I love the new handlebars...salsa poco). The LBS guy showed me the stock ones and the salsa side-by side and it was pretty obvious that since the curvature started sooner, the reach was shortened. However, I am thinking the same thing you are in regards to that change should be enough if what the original LBS said was right about it being okay but not an optimal fit. Maybe there is something else going on that I'm not pinpointing.

All this talk about going in TODAY is making me panic but I'm going to hold off til Monday. The man who helped me out doesn't work Fri/Sat (I'm working right near til their closing time today) and he requested I come in Monday because Sundays are busier and he wants to be able to spend a lot of time with me. I'm sure he has a superior who has the final say if things don't work out, but I'd like an advocate there who is familiar with me.

I don't want to make the LBS sound bad because they were really very helpful and it isn't their fault I bought the bike. I do feel that the reason they don't do a very comprehensive fit upon purchase is because they have a supposed fitting guru working there who charges $150-300 for a super high-tech fit session. This rubs me the wrong way, but shame on me for not making sure I'd be getting a comprehensive fit before I purchased. To their credit, they never tried to sell me this session, either.

I've worked in a retail setting before and know that even with a no-refunds policy (and I worked at a place that made you sign saying you knew of this) loud, angry customers usually get their money back. I don't have the personality to raise such a stink, though, so I'm really hoping this will work out fit-wise or return-wise with things staying civil.

I'm going to go on Monday and hope they can dial in a fit for me then go from there. Right now, I can have a slight bend in my arms, but it is more comfortable to keep them straight. I'm not sure if this is fit or my lack of strength in this position.

I've read about that bar-obcuring-hubs thing and with my hands on the straight portion of the bars, it lines up perfectly. If I'm on the hoods, it doesn't. I searched this forum and read somewhere about someone saying you should extend you arm from elbow to fingers from the seat and this should bring you within 2 cm of the middle of the bars. I'm about an inch off from that mark now.

The Onix does come in one size smaller, but that model has 650cc wheels. The woman who originally helped me with the stock-onix thought I wasn't "that short" to warrant trying that size (I'm about 5'2").

Again, I'm new to this so am not entirely sure what to look for. Maybe the Onix does fit but is more aggresive. Maybe the Trek feels great now but I'd "outgrow" the geometry down the road.

I am totally stressing, though and this isn't fun