Interested in these too man, Had a search about - seen a few horror stories where the bolts included with them can vibrate loose, wheel comes off and you get some serious lows!
also: The delta mics are steel - so heavier than alu ones from the likes of M.A.D (£70 for 25mm) which if your really weight conscious may be worth considering
The consensus seems to be if you get them, to get better bolts for them or make sure they're definitely torqued up high enough.
Is fitting spacers as simple as bolt them on and away you go? Or do you then also need the tracking etc sorted? I read that widening the track can throw the handling well off, though surely if anything - it'd be better being wider and lower?