While some folks' mileage may vary... I was VERY pleased after upgrading from my 6000U to a ViP622. While I was getting pretty good signals OTA, I did get breakups on a couple of them sometimes.
But since getting my ViP622, and making no other changes to my antenna setup... all my signal levels jumped and are much more solid now. There are the occassional glitches, sometimes network problems (like a week or two ago when Raleigh 5 and 50 were lost after a construction accident for several hours!)... but all my good channels before are now great, and my marginal channels became good to very good.
I also have another standalone digital receiver, and my ViP622 is better than that also... and it had been better than my 6000U as well... so OTA-wise, I honestly would expect you to have better results than you are experiencing now if you get a ViP622.
But since getting my ViP622, and making no other changes to my antenna setup... all my signal levels jumped and are much more solid now. There are the occassional glitches, sometimes network problems (like a week or two ago when Raleigh 5 and 50 were lost after a construction accident for several hours!)... but all my good channels before are now great, and my marginal channels became good to very good.
I also have another standalone digital receiver, and my ViP622 is better than that also... and it had been better than my 6000U as well... so OTA-wise, I honestly would expect you to have better results than you are experiencing now if you get a ViP622.