They're actually the exact same bars and stems - both are Cannondale 3s (the new bike has newer versions with different graphics, but the length/angle/reach/drop/sweep/etc is identical). When I put the bikes next to each other and rotated the bars on the new bike to match the old, it was like I was seeing double for a moment. The component groups are slightly different - the CAAD12 has an Ultegra Di2 R8050 group, while the SSEvo has a mechanical R7020 hydraulic disc setup with the huge reservoirs - but the distance from the back of the bars to the curve in the brake hoods is identical, too.

There are occasionally advantages to being a Cannondale nut. ;) (I also have an old R500-ish model built on the 2.8 frame from the early 90s with a custom paint job, back when they were made in Pennsylvania. I know these frames have little to do with that one, even though the CAAD12 is a descendant of the the 2.8. But I inexplicably like Cannondale. There's no sane reason for it. My gravel bike is a steel Velo Orange, though, so I'm not completely nuts.)

You did make me think of something, though: I'll double check that the angle of the bars is the same. It's possible I made the new bike's angle too low by accident. That would certainly contribute to this issue.

I actually already ordered the seat post. and it's on the way. :) Given the extremely similar geometry of the two frames, I assumed I would need it when I bought the bike. I thought I might avoid it when I saw how much adjustment the saddle had, but after the first ride, I was convinced that I'm going to need the post. If nothing else, it'll give me more adjustability in the saddle position than I have now (the saddle is all the way forward, so the only adjustments available make the reach longer) and save a little weight.

As similar as the two frames are, the saddles are completely different. The CAAD12 has a Specialized Power Arc saddle that I got during the fit. The Evo has a Selle SMP Dynamic Saddle. The latter is longer than the Power Arc, so it's hard to compare the two for position. If I measure from the nose, which is what's given in my fit report, I don't get the same effective reach. I tried to use the rear of the saddle to line them up, but that obviously hasn't worked. I'm hoping the SMP saddle works for me; if not, I'll get another Power Arc saddle for the SSEvo. (I intend to keep both bikes long term.)