I think adding the rhinos adds a lot more than the dreadnoughts did, though as we discussed you need to be ready to swap tactics and turn into an assault army if you're playing against a gun line.
The grand master is always going to be attached to one squad. That squad can't fit into a rhino. If you drop the rhino from one squad and can scrape together 5 points from somewhere else, you can give the GM his psycannon back - and a relentless BS6 psycannon is pretty awesome.
EDIT: We both also probably should make Grand Strategy tokens to stick with our squads... because I don't know how many rounds of shooting finished with the phrase, "Oh, and I should have rerolled my 1's. Oops."