And this from a married man.... you're leaning against an open door there big guycampbell wrote: a full set of BJs is never a bad thing I guess.
Campbell

However - things already mentioned re. lightness and MMC's aside, having owned S1's both sides of the millenium ('97, '99 & '00) , I can honestly say that the only thing the '97 car had against the '99 and post 2K car, was the MMC brakes. I never noticed any other difference on road or track and would gladly have any of them again.
Of course, if there was a difference in cost, go for the cheaper one as that will leave more in the kitty for inevitable upgrades later on

HTH