Glitches? There aren't really any glitches as such anymore, SLI has come on leaps and bounds. Yeah, there are a few games here or there which don't work with SLI, but in my own experience these have only really been games where a second card doesn't even matter or make a difference anyway (indie games, early access games, etc).
Personally I've always found two mid-range cards a better option for pairing up, because then you spend less than the highest tier card while also getting more performance. Honestly I don't see why there aren't more dual GPU solutions about, such as the ROG 760.