Perhaps there are other reasons than "slower box" - a large number of clones and forcing them to buy new tuners ...
I think this is not fair ...

I'm owner of 800HD - ORIGINAL 800HD from DMM - thanks DMM for no more support for this box !

DMM - if You don't release a new kernel for the 800HD, the oldest owners of HD receivers will be very dissatisfied and cheated by DMM.