I see no appreciable difference between the 622 & 722 HDMI (on my 61" 1080p DLP w/receivers set to output @ 1080i). I can give you a pretty good amateur A/B comparison as I have both a 622 and a 722 connected to the same set and have been switching back and forth between them all day.
What I
can tell you is that quite some time ago, when I decided to utilize HDMI on my 622, is that HDMI required much more calibrating and tweaking than component. "Washed-out" tends to be the general concensus with regard to initial impressions of HDMI on this box. However, it
can be overcome with calibrating and tweaking with patience. At which point HDMI is
equal to component (in my opinion), but it does
not exceed the quality of component as one may expect. There was no trial-and-error while setting up the set for the 722's HDMI because I already knew the exact numbers based on settings from the 622's port.
Now, you
may be hearing about the overall
reliability of the HDMI
port on the 622. It's been hypothesized that earlier models of the 622 had delicate ports that were prone to failure. I believe,
based on ralfyguy's report, that the port was "beefed up" for the 722 if not on later models of the 622. I have one of the earlier 622 models (as indicated by the letter "A" at the end of the serial number), and I've had zero reliability problems. That said, I haven't tempted fate either. I've been very careful to avoid stressing the port and the cable enters the cabinet through a convenient porthole that is level with the point of entry on the 622.