I've sailed several boats with in mast furling
in winds ranging from 20-30 kts and only had trouble furling
on two of them. Both because the boats were recently rigged and the halyards stretched from the heavier winds. On one I tensioned the halyard and all was well. On the other I waited for a lull, headed up and worked it back in. In both cases I should have reefed sooner than I did. If I had done so I doubt I would have had issues with either.
As for less power that's more of an issue with the older mains without the battens. Still not the same as a full main but much better than they were. No problems hitting hull speeds so not an issue in my book.