I agree with the comment that the Rival is more effective from straighter angles, unless there's a ton of backend on the lanes.  I've been able to use a Rival from inside angles, but the backends have to be flying in order to carry corners consistently.  I just bought a Momentum, and I haven't really haven't put enough games on it to see if it would work well for this purpose.  So far, I've used the Momentum when I need a cleaner look thru the front, or a little more backend, but I'm still playing pretty straight with it.  I also bought a Wrath DF that once the lanes dry up a bit, works really well from deeper angles.  Personally, I'd go with a Wrath HF or DF for that purpose rather than a Momentum.

Agreed, the Wrath DF definitely needs a little dry to bank off of.  But from what I've seen so far, it's king for that late 2nd/ 3rd game league shot where the lanes break down.