I love both games.
Probably the fact that I played ST 2 first impedes me to feel disappointed about it, because it is really different in relation to its predecessor.
However I have always loved Mercs, and these two games give me similar feelings.
I hate slowdown in any game, however it does not always bother me. In this case the slowdown is not very accused and it does not bother me and I do not think it is really necessary. I am more bothered by MS2’s one.
About jumping or rolling, well I prefer rolling, I think it makes more sense in this kind of games, unless you are able to jump somewhere, which is not the case.