Re: How much wave/swell is too much?
Swells, not so big a problem. Waves, breaking waves, more of a problem. I'd say by the time you get eight-foot waves on a 30' boat, the biggest problem will be seasickness or fatigued crew, and some points of sail or some maneuvers (like turning around) may become dangerous as you have to come sideways to the waves.
OTOH I've been out in 8' and 40+knot winds in a 28' boat and wile it was a tiring ride, we never felt it was dangerous. Mainly because everyone on board had been out, gradually, in conditions working up to that before.
The mythical prudent mariner would say "Gee, maybe that's too much for us..." and just take some more time working up the comfort level and experience. Nothing wrong with that. If anyone complains, let them buy the life insurance.