Would it be 100p=1$ ? Like 20$ commission would cost 2000p? Or you add more extra for withdrawal(as long as you're a premium your withdrawals don't cost extra fee)? Or just more? You could just decide on your predicator how many points equal 1$ and use it for the split payments^^ Normally it's 100p to 1$ (some people get it wrong and take 80p for 1$ which doesn't work if you're paid with points but works when you buy points, it's like 1$->80p->0.80$ etc. because of that 20% DA takes when converting; in general it's bad to buy points just to buy a commission, that's why the split payment option would be nice)
I would say you should try both. Give underaged the possibity to get art from you. I would die for a piece from you, too. I hope I will get in the future the chance to commish you for my punk. :'D Oh and... well... I have an open (RP)marriage. We thought it would be great to commish ya for a picture of these two guys. But later. Anyway. Thats my opinion, I hope I could help ya a bit.
If you ask me, I'd say Both, because your art is hella rad and gorgeous, but there are people who cannot afford them because they've got no paypal yet, for example ME //smacked - - - If you'd keep that point commission widget open, for a longer time than just week or so, a lot more people would consider commissioning you. Because some have a lot of points, but are underage.