The best I can receive the DATV beacon when completely empty of activity and a good clear sky is 10.4 MER on my 1.05m offset dish, I spent some time checking it for alignment and that was the best I could get. The software I use is Longmynd, I use a POTY feed and a standard crystal'd LNB .
One extra thing I have in there is a 749 ish MHz is bandpass filter to reduce the front end noise window slightly to the Minitiouner-express. I think that when tested it gave me a 0.5dB improvement in MER with it to without it. One other station on the SAT at present, cloudy sky and I am at MER 10.0. So for my best guess with a similar size dish and standard LNB no filters would be at MER 9.5 and you would have a good RX.