Yes the ZR is good, as far as swapping it out for an Edge goes probaby no. The body's kind of thin, although I don't think it's impossible as the older Sabre's had Edge tremolos, however you'd have to gouge huge chunks out of it to make it fit.
Actually called Mark!

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People with a duck for their avatar always give good advice.

...it's a seagull

Quote by Dave_Mc
i wanna see a clip of a recto buying some groceries.

i love the ZR trem, perfect IMO, it's been compared to Kahler which is many people's prefered trem.

Edge is good but it's a bit pointless switching out a perfect trem for a perfect trem.
All S series guitars before 2003 (or 2002, whenever the ZR bridge was released) had Edge and Lo-Pro Edge tremolos on them. It should fit into the body, but you will need to drill holes for the pivot inserts as well as maybe a new trem claw. Not to mention change the cavity shape, as I have a feeling the ZR bridge is shorter than the Edge.