I ordered this:

ECU DELPHI 28250531
  - Model: 0800-174000-2000   MICF0800-174000   1   $291.13   $291.13


The vendor was in China, took a while to get the part but it was definitely worth it.

I also did the Powersports tuning route on the existing ECU since it was relatively inexpensive, can't say I see a huge difference? 

The new ECU DID make a big difference on performance, but I still had an occasional cold re-start.  The powersports tune seems to be better, I'm running that at the moment, seems to be a touch better throttle response/low RPM engagement.

I joined this forum specifically looking to solve this problem with my new 2022 UForce 800.  Ordered the ZForce ECU, installed it yesterday, fixed the problem like everyone else has reported!  I don't know how the ECU change has had such a big impact on low RPM engagement of the CVT, but it has...