One thing to take into account. I believe that the number of people experiencing problems is not as great as one might think reading through these boards. It's been mentioned by the moderators that there has been a large influx of new users in the last several months. A good number of those are attributable to the HR20. And of those new users, I would imagine the majority of them are here BECAUSE they're experiencing problems.
So if 1 out of 4 on these boards are experiencing major issues, the number in the grand scheme of things might be 1 in 10 or something of that nature. (And for those of you number hounds, I'm just pulling numbers out of my rear. Maybe its 1 in 7, maybe it's 1 in 20. I don't know. But if it's 1 in 4 here, I'd put money up that it's not 1 in 4 across ALL installations).
And, as many have said, keept the R10 running for a while until you're comfortable with the HR20. If your HR20 misbehaves, you'll have the R10. I will say though that I replaced an old Hughes DVR40, and I did NOT keep it running as a backup. I've been fortunate enough to have NO problems to this point, so it may very well be that you'll have the R10 put away before you know it...