Barney can screw any piar of cranks up, if they were the new un-roundable cranks he would manage to.
IMO if your bike originally came with sq.taper stay with it, ifit came with ISIS stay with it, the pro's and cons weigh out in the end.
Bearings in ISIS are smaller but I've got a year old truvativ bb which is still going strong, the tapers do seem to round abit easier if taken off alot but how many people take their cranks off more than once a month. The axles are stronger in ISIS bb's and can be hollowed out without loosing too much strenth.
Ive never run Sq.taper so I can't comment much on that.