Loads during a spin are complex, poorly understood, but generally unlikely to damage the aeroplane. They should be well within the design loads.
It is however NOT a 1g manoeuvre. I've seen a couple of g in both directions, and somewhat more than 0 sideways on occasion. The loads can be quite oscillatory.
If an aeroplane is going to be broken in the spin however, other than the obvious ground imapact risk, it's almost always going to be either overspeed or overstress in the resultant dive and pull out.
That said, I have seen a propeller damaged; it was a Tucano, doing oscillatory spins, full power - so high powered turboprop, with a high mass prop, in a very oscillatory spin mode. It's a pretty rare set of conditions and I'd not get worried about it in the vast majority of GA types.
G