A few bad ones and you're ready to look elsewhere. Remember, people will let you know w/o thought what they think when something doesn't do what it states. People don't get on to tell you , Hay, this worked just as described, this is great!!!!! Doesn't happen. I know you asked, so there for you got some replies.
The Clarion HU's are still top notch. Their HU's do their rated power. I'm not saying that the one poster didn't know how to test for the voltage output, but every review I've read they DO or surpass their rated output.
I've had 3 Clarion HU's myself, and my next one to replace my Eclipse AVN6620 will be the Clarion NX501. My first ever HU was the Clarion 6770, sold to get the DRX9175L, stolen so I bought the DRX9375r. The only issue I've ever had w/any of these is the 9375 started to act up accepting CD's, after 6 yrs of service and non-stop playing.
I also have:
5632CD
5780
7770
ADCS-1
DRX7475
DRX8275
DRX9375r
DRX9575Rz
DRX9675
HX-D10
DXZ615
Except for the 5632CD, all work perfectly. The 5632CD works, but the display has faded and the #2 preset button fell off.
Chances are, the unit you get will have 0 issues for years to come. Just like cars, some are lemons while its sibling isn't.