Question - does he do this with Clomid? Because Clomid for us is getting 75% just on its own and it's my personal belief that any apparent effect of sperm spinning is probably an artifact of the Clomid and not the sperm spinning doing anything.
The problem with IUI is that it's quite lower odds of conception. IT's a miracle for people who really cannot get pg on their own without it, but those of us who can, it's much lower chances and considering the cost of each go-round, I personally don't think it's at all worth it.
Some people have thought about swaying with sperm spinning and if you're going to go that route, I would def. throw some sway tactics at it. You'll need to be careful though, not to cut odds of conception too far. Many of the supplements are not going to be appropriate for you and you'd have to be verrry careful not to go overboard with diet and exercise or you'll stop ovulation and then you'll have a big pain in the butt to get it going again.