I've completed a few insane ironman runs. It's generally not too bad. Bugs aren't really an issue since if you were going to die to any of the relatively minor problems the bugs present, then you were going to lose anyway.
For example, the teleporting enemies glitch is actually useful in insane. Because what happens in insane is your team will always be moving a super slow snail's pace from cover to cover, staying as far away from everything as possible. So when enemies teleport into the middle of your squad, you will cut them down before they even get anywhere thanks to reaction fire, the proximity, as well as their lack of cover. It's kinda like the missions where thin men drop from the sky, except in sets of 3.
So yeah, as someone who's done them quite a few times. It's not the biggest deal and you can easily circumvent the issues. Though of course I might not recommend it if you don't take trial and error well as the problems with insane come from the crazy buffs the enemies get... not really the bugs.
I also highly recommend you rush for laser and plasma weapons above all else. Armour is useless in insane unless you're in full titan or something like that. Carapace still gets you killed in one shot. If you manage to get a good sniper with laser or better, he alone is going to carry you to victory.