I assume you have software rev 266. The 811 is definitely more picky on signal from what I have seen but once locked it is rock solid from my experience. As for there still being a software issue.. This is hard to tell since OTA is an art to begin with and I am sure you might get mixed opinions on this one. By the way. in my case the 811 OTA is performing better than the 6000 did.
I am sure you have tried the obvious to give the 811 the best chance:
1) Checked treeline etc. Does this seem to occur on windy days. I had some palm trees that would grow over time and when the wind picked up I would start to lose SAT signal. It happens.
2) I have a preamp and rectifier on my OTA. This allows for some adjustment and improved the reliability of my signal. My signal is rock solid to the point I don't notice it.. (They way it should be)
3) The 811 seems more senstive to Multipathing. This is were most people thing there is a bug still in the 811.
Like RAD said, search the 811 forum. There are reports and opinions. But the level of OTA issues on the 811 have gone down from what I can tell with 266. Same with the svideo, but there are still reports that for some it is still an issue.
There is a thread on here
http://www.satelliteguys.us/showthread.php?t=19040 that mentions getting an 811 with a dishpro logo on it that solved their OTA issues.