In Europe there's about 750, 800 Dollars difference between both guitars, If there was only 200 dollars difference, I wouldn't hesitate one moment to buy a gorgeous Olympic white John Mayer strat with the very dark (african rosewood) fretboard. With it's mint pickguard, it looks alot like the '62 reissue. It's got a very light body (ash?) and a slighter thicker neck than the standard, but it is very comfortable!! And the Big Dipper single coils sound FANTASTIC! DO IT ! DO IT ! DO IT !
directed to the topic starter, here is my Two Cents:
as a collector of JM strats, I scoff at the comparison of one to a mere standard. the JM has so many advantages over a standard, or even an american standard. firstly, it has a set of Big Dippers, which are very close to FCS '69s spec wise. so you are getting a set of very sweet and saturated pickups there. 2nd off, it has a satin-finished neck, so you have no problems with hands sticking to the lacquer. if you liked the neck, then I say go with the mayer.
of course, I'm not suggesting don't try the american standard. I'm just saying that if you like it, buy it.