I've also implemented this features in my softwares. It seems I've no longer problems with ISP.

For IAP, not that the only limitation is to keep P2.6 and P2.7 help to high in your application.
I've experienced a graphic LCD which wasn't agree at all and puts its pins to low when reset occurs.
You should take it into accunt when designing your application hardware. I would be a pity to be unable to use IAP because of a peripheral which pull down the lines....

Regards
Stephane