If you do decide to go with reliance I suggest you dont disconnect your bsnl broadband connection for atleast one month... see how reliance wimax fares as I have heard too many bad things about reliance wimax and almost all of them are true to some extent.

Reliance wimax has had issues right from day one..
Upload problem
It takes ages to get an ip assigned when you start the connection which might take more then an hour at times.

Besides that there are a lot of other issues which Reliance claims have been sorted now.

The best thing is to experiment forst and see how it does for you instead of getting rid of bsnl at the same time.