The Arch Rival was cleaner thru the front part of the lane and stronger downlane when compared to the original.  Bowling on league shots can mask the cleaner thru the front part and just show the stronger downlane motion providing the illusion that it's stronger when it really isn't.  

The Sharp Noize has nearly the same coverstock as the Arch Rival with a higher RG/lower differential core.  It really depends on what you liked about the Arch Rival.  If you liked the oil handling characteristics which are more cover driven, you could go with a Sharp Noize and take the cover to 4000.  If you like the shape of the shot, you might be better off looking at the raw Hammer series (probably a Burn) to get what you're looking for.  A Burst might work, but in general it roll earlier and won't flip quite as hard as the Arch Rival did.