Hi cburbs,
I currently am running the HCA3500 (350 watts RMS x 2, 20 Hz - 20 kHz, 8 ohms. 120 amperes peak per channel) for the front 2 channels, HCA 2003A (220 watts RMS x 3, 20 Hz - 20 kHz, 8 ohms. 60 amperes peak, per channel) for the center and rear surrounds. I have 2more QS8’s for the side surrounds that I have not installed due to a remodeling project that I have been putting off. When I get the additional speakers installed they will be powered by the HCA2003 and I will use the HCA1206 in bridged mode (350 watts RMS, 20 Hz - 20 kHz, 8 ohms, each bridged channel. 30 amperes peak, per channel) to power the rear surrounds. The 2 spare channels on the 1206 will be used for the second zone in the kitchen (135 watts RMS x 6, 20 Hz - 20 kHz, 8 ohms, all channels driven. 30 amperes peak, per channel). I also plan on adding a pair of massive subs and using the HCA2200 bridged (1000 watts RMS, 20 Hz-20 kHz, 4 ohms. 50 amperes continuous 90 amperes peak) to power them. I have played with all of the above-mentioned amps in a few different locations using many different speaker configurations, most was 2 channel stereo. In short the only noticeable difference (other than volume) was the lack of bass from the HCA1206 in non bridged mode. It is not that it was missing but compared to the other three amps it was not as abundant. As soon as I bridged the HCA1206 it sound very similar to all of the other Parasound amps that I use. I wouldn’t be surprised if there were an issue with the power supply in my HCA1206 that is contributing to the sound difference. I have noticed some 60 cycle hum coming from the speakers after long periods of play, 4+ hours. Since I plan on using it in bridged mode for the home theater surrounds and the other 2 channels only for background music for the kitchen I am not planning on getting it looked at. Of course that may change if it gets worse or it lets the smoke out.

I can’t speak for the HCA855 since I never have seen one but have been told that it is a good sounding amp especially for the money. Even if this amp does not supply massive bottom end you may not notice it in home theater mode because you can send all of the low-end bass to the sub.
I think that you are on the right track planning on testing a few amps and systems. I have been surprised more than once by taking the time to do live head to head testing. If you are not happy with the sound that you get from your current amp selection try looking at the older high-end 2 channel amps. A stack of the OnkyoM-501, M-502, M-503, M-504 or the Denon POA2400’s would make a great amplifier section for the Outlaw 950. The outlaw amps have been rated very highly for sound and build quality. They should represent a great value in a new amp purchase. My original intent was to go all Outlaw but I purchased the Parasound HCA2003a for my office and got hooked on their products.
I am not sure where you live but I am in Rhode Island and if you are close by and want to hear the Outlaw/Parasound/Axiom system I am running please let me know and we will make arrangements to shake the house.
Sorry for the long post, I was on a roll.

Thanks,
Greg