So my rectifier is busted, my local bike shop has plenty with the same bolt placement and 5 prong connection - but none for my cbr600 F2. Can I just grab one of theirs off the shelf and set it up or is it going to perform diferently than the OEM one for my bike?

 

NOPE !
They may look the same on the outside, but that doesn't mean they are the same on the inside.
Buy the right one for your bike................

 

They differ in the regulator voltage setting. If you do make the plunge, put a meter on the battery while the bike is running and rev it to make sure it doesn't over-charge.
Here is a great resource on aftermarket motorcycle charging system parts. These also have a one year warranty.....OE elecronic parts DON'T. You can also use this site as a guide on what reg/recs are interchangable as it gives you OEM part number that the elecrosport part replaces.....
http://www.electrosport.com/street/r...rectifiers.php