I have been listening to the 8C for six months now, upgraded from 8b. For $1500, the upgrade is a no brainer, absolutely!
The plate amp / DSP is from Dayton Audio and houses a 250W amp, class D (? ). The initial concern was that the A-D and D-A conversions would degrade SQ. I know there are person here who claims to be able to hear and dislike a DSP in the signal path. I had some problems initially with the sound from the vinyl side of my system whereas the CPD played wonderfully from the get go. But now as I listen to records, I cannot tell what the DSP is doing negatively to the sound.
There are a couple of settings that Bruce has left to the listener's discretion: the volume of the woofer is adjustable relative to the panels and there is a Time Delay setting to time align the woofer and the panels. I have left the other adjustments ( a total of 7 ) as factory settings. But a fellow over at the AudioKarma forum who is a sound engineer has fine tuned the other settings with measuring software, and he claims the quality of the bass goes up a few notches.
Compared to the 8b, the 8c is a new speaker. It is full range, holographic in soundstage, blends better with the my room, and much more matured / sophisticated.
It would be very interesting to see what Steve Guttenberg has to say about the 8c since he mentioned that a follow up to the 8b will be in a future installment.