Agree with Stephen, original question :
"Opinions? What is the maximum wind speed you would go out in? This would be in protected waters (low/mild chop) and just for fun (and say you haven't sailed in the last 2 months)."

Like riding a bicycle, the 2 month gap should have little bearing on windstrength you feel comfortable sailing for fun in, unless you only sail 6 times a year.
18-22knots(max gust) is probably ideal and is most catamaran`s design range. Yes we`ve all been caught out in a bit more at times. I would say 15knots sustained gusting to 18 would be the best conditions you could ask for. Unfortunatel y where I sail when it`s 15knots the gusts are going into the mid 20`s, makes it difficult to set the power and keep it on.
This is probably the biggest deciding factor together with sea / water state : gust factor of 7knots will make an average of 12knots hard to sail in (ie 5knots gusting 19, a variation of 7knots either way.) It`s much easier to sail in 22knots gusting to 25.
But in 22-25knots you really should be kitesurfing or boardsailing . I attended an informal speedsailing competition as a spectator last weekend, 22-28knots winds (measured), max speed was 42.03 on a board, and a shade over 40 on a kiteboard. Olaf Marting was on form (kitesurfing 500m world record holder, just over 41knots), and was 2nd fastest. I put my arm through my sail the day before , so will have to wait for the next event to see how slow I am.