IIRC, I was receiving Monster HD on 9481 with my 811 before I upgraded, so if you currently have the original 10 voom channels you should have that one. Can you still add those channels to the old HD Pak? (That was the combination I originally had for $14.99 per month minus a $5 credit.)
To get all the new HD channels including the 5 new voom channels you now need one of the ViP receivers (211 or 622) and at least HD Bronze programming. If you were receiving the 10 voom channels before then you probably do not need to add any equipment. If not, then you can either swap your current D500 for a D1000 that would add the 129 sat., or add a second dish (D300 or D500) that you could point to either 129 or 61.5 if that location has better signal strength for you. (Most of the "national" HD programming is the same on 61.5 and 129.)
Can you (or will you eventually be able to) receive any local channels in HD from E* in your DMA? If so they are most likely on the 129 sat., so if you want those channels that makes the decision for you. Otherwise either sat. is a viable option. How many receivers will you have? What equipment do you have now (what LNB(s), switch, etc.) Answers to those questions will determine the best path to take.
I had an 811 with a 2-dish installation done in Dec. (leased). I then purchased a 622 and did the swap-out myself. I using the 811 in another location since I still have time remaining on my original commitment. E* allowed me to do the 622 "installation" myself and I called their Tech Service to activate it, which they did with no hassle. I originally kept the old HD Pak w/voom (15 HD channels), plus AT60 and locals, but that did not get me any of the new HD channels. I eventually changed to HD Bronze to get the all the HD channels on the 622 (except premiums and NGHD, 26 total?) and the rest stayed the same. This new programming actually worked out to be $1 per month cheaper and there is no "HD access fee" as I was paying with the old package, and no lease fee since I own the 622.
In understand E* is much more restrictive with self-installs these days, and if you need additional equipment (new dish or whatever) then you're probably better off letting them handle it anyway. If they won't initially agree to a self-install with an owned 622, keep calling until you get a tech who will. YMMV...