yes it is
My dad has 3 of them in various rooms of his house. The 301/311 is very much supported
(the 311 originally had an embedded card while the 301 had a card to be pulled out. That point is now moot after Dish did the card upgrade)
Just add it to your account and check your sub channels, if those blanks complain to Dish, but do not say any word about 'smart card' and a color of it. Else you will end-up to pay for it.
I can see Dish doing away with the receivers without 8PSK that new SD local markets require (301, legacy receivers, etc). They are already starting to ship replacements as MPEG-4's.