Why bother with reviews? Just audition the HCA-2 with the free 30 day trial period from PS Audio. Since you haven't even listened to this amp at all, it makes no sense reading what others have to say. When a unit is priced as low as the PS Audio and rated as high, it becomes obvious that many people would like to find fault with it to justify the fact that it isn't quite up to task. I own the HCA-2 and have had the opportunity to listen to far more expensive amps but it wasn't the price that drew me to it, even though I could afford more- it was the sound. The bass was sufficient- heck- I am using it to drive ML Aerius i's and have successfully driven Maggies 1.6 with no problem at all.
The 250 is slightly better (more power, resolution, and harmonic richness) but it is a different beast altogether (it is not a digital hybrid amp). Yet the difference is only about 5-10% improvement over the HCA-2 (to my ears anyways). It may justify the extra cost but to be honest I could find little to complain about the HCA-2- it presents music in a very open and honest way without exaggeration.
Just audition the amp before relying on the opinion of others. If it doesn't work out, just return it with your money back. You have nothing to lose. Your ears are the best judges in your personal audio preferences.