well they would certainly work. i do like tim's t-top clones alot, but after a recent few pickup swaps i can also appreciate what tim's done with the riff raffs.
the extra hair, bite, and reduced mids of the riff raffs vs the t-tops are all audible, but like you said once before Dave with PAFs its more of a flavour than a night and day shift.
the t-tops have a beautiful openness and subtlety to them which the riff raffs i think can sometimes lack (in comparison). on the other hand the riff raffs are more rawk...
the a5 mule bridge is a great pickup, but i'd hazard that might be too thick in the mids for what you are looking for.
i'd lean more towards riff raffs perhaps myself, it seems like the guitar is naturally quite thick in the mids, and the extra bite of the riff raff might add a bit of brightness.
though if you have an amp with a decent amount of drive (a little more than jcm800 levels) you'll find the t-tops more versatile... i can certainly nail an early rudolf schenker rhythm tone with them for example, but the slightly lower output vs the riff raffs is noticeable.
edit: regarding covers, that makes a difference on real t-tops (i've only tried tim's with covers on) in terms of brightness and output when you take them off
