Look, lots of people say no, lots of people say it's fine. Personally, given the data at hand, I think it makes more sense to buy a non polygonally rifled barrel to shoot lead out of. It's not that I disbelieve the guys that have had success with lead, it's simply that hard data from multiple sources seems to indicate that it is at the very least not a great idea. Additionally, in this case I think caution is advisable. I would much rather spend the extra coin and feel safer shooting lead than not do it and always be worried that something is going to go south at any moment.
That's just my take, so for you people that have had success shooting lead, don't take it as a personal affront or an attempt to discredit your success. I believe you, I just personally would not feel comfortable is all.