I switched from D* to E* back in 99. Though I didn't have HD back then, I can tell you without a doubt that I was happy about the switch and have never looked back.
I currently have a 508 and an 811. The DVR functions of the 508 and 522 should work similarly. Basically, you can schedule recordings in 3 different ways.
1- Easiest- you can open the guide, tune the guide to the channel you want and then select the program you want to record. It will prompt you for info, such as, do you want to record to PVR, record to VCR, or just auto tune. The it will ask you if you want to record once, daily, weekly or M-F
2-you can go into your menu, select timers and manually enter channel, time and frequency
3- hit the # key, it brings up a search function, then type in the title of the show you are looking for and hit enter. It will then search the guides for show you are looking for. It will list times and channels that show is on. Just select the one you want and then select your recording options
The problem occurs when the program you want is preempted for something else or if the program guide is incorrect. Meaning that if you have Alias scheduled to record on Sunday @ 9PM EST, on ABC, the 522 will record what ever is on ABC on Sunday night @ 9PM EST, whether it is Alias or not. 98% of the time you will not have problem
As far as the 811, I was one of the first customers to get an 811, I was installed within the first week they were released. While the 811 does have bugs, I think the overall performance outweighs the bugs. I also know that E* will send the fixes through software updates eventually. I think the biggest difference you will find is that D* receivers do not require any kind of D* programming to get your OTA locals. E* will not allow OTA locals on any of their HD receivers without programing from them.
Now, my situation may be different b/c I do not need to necessarily watch HD through my 811, b/c my TV has a built in HD tuner, so I can watch my HD locals through my Mitsu.