I also have a 508 and am about to change over to EA (as soon as I finish recording programs off the 508, now in progress).
The question is, regarding the 508 DVR: If they replace each, even for free, and even if the replacements are Leased rather than Owned - won't we still be required to pay an extra fee each month for that/those "extra" receiver(s)? The 508s are, you may recall, grandfathered as far as the DVR fee goes. But now there's just the "one" DVR fee, regardless of how many. But their per receiver fees apply.
So if we accept replacements for the 508, won't we be paying more each month anyway, all other things remaining constant? Might be better to just sell or toss the 508 & do without, if it's little used.
I, for one, would not accept a non-DVR replacement. It would have to be, at a minimum, a ViP612, and be able to share EHDs with my two ViP722 units. The TV that has my 508 attached is a 36" SDTV, but that won't always be the case.