I pay my 4DTV subscription annually. Much cheaper that way. But I think you can pay monthly if you chose with most programing providers.
I pay about $500 annually. To get that same programing on DN/DTV would cost well over $1K, and you can't even get some of the channels on little dish. This is the programer I deal with, but there are a few others also.
http://www.callnps.com/
The difference? Wow, where to start. Better picture quality, much more channel choices, cheaper programing pricing,more than one programing provider to choose from, non encrypted anolog channels and many wild feeds of sports,news and so forth. Plus I love tinkiering with the big dish stuff.
Mainly the reason for the big dish for DVB. The ability to receive the
c-band dvb signals as well as the ku greatly increases the number of channels you can receive.