Both my 6000s alive and well....
Add 2 more to the count -- both have 8PSK & 8VSB modules. (Did do the fan replacement on the 8VSB modules so they run cooler, quieter, and longer.)
Menus/guide not a real problem... I take notes when I surf the EPG on the 921, and can set the timer manually on the 6000s if I need to.
Both 6000s still have excellent HD PQ, very good OTA, and have been very, very reliable. With the recent OTA issues with the 921, I just did my OTA watching on the downstairs HDTV with it's 6000. -- Just wish the 921 "backup insurance" didn't cost $5/month!