Apologies, as you probably noticed I was still discovering about the program and editing my post on-the-fly. You are of course right.. keeping the points in their 'native' currency will always yield the highest value.
However that does require for you to be into Accor. Personally I do stay with them a few times per year at the lower end properties (Ibis, Novotel) but can't say that I have been very impressed for their price. The Sofitel hotels I've tried were good..but generally a bit out of budget.
So if you don't use them often enough to earn points for anything meaningful, you may as well convert the points into FB miles. But I agree that if you have a chance to reach an amount that allows for a hotel night redemption - that is probably the better value.