The 811 will also be a decent HD OTA receiver for the foreseeable future regardless of what E* does with their content. You have a certain amount of MPEG-2 HD content that you will continue to receive probably for several years as the conversion of fielded receivers continues. But in that interim all new channels will be added in MPEG-4 (coded or headered) only, so you're missing that capability.
When I initially upgraded to my purchased 622 I kept the old HD Pack / voom / AT60 / locals that I was receiving with the 811 (which I'm still using). I knew that once I gave up that programming I could never get it back. But I was already missing the 5 new voom channels and ESPN2HD, Universal, etc. that the 622 could receive that my programming did not provide. During one call to Tech Service, the tech initiated a conversation on why I did not convert. It turned out that it was actually $1 per month cheaper to switch to HDBronze/locals, and I would could get all the HD programming offered at the time as well as the several new channels added since then! That actually offers a payback on the upgrade cost, albeit in my case it's quite long! So you should also consider the limitations the 811 is imposing on your programming options.
It is possible that E* will ultimately swap-out the remaining 811s for 211s or whatever at no additional cost to the sub. just to get them out of service. And I suppose you could try to upgrade to a metallic pack with the 811 (I haven't heard of anyone doing that) comparable to what you have now and possibly save a buck a month or so. Otherwise I agree with others - as soon as you don't have a commitment you should upgrade. Essentially more for less, but of course, YMMV...!
Welcome, BTW!