Nope, I've never had any problems getting it up in front of (and for
) other guys
--but I don't think that's relevant to your situation, is it...?
But seriously, I believe this is a dilemma that you have to decide for yourself. It would seem that you are leaning toward accepting, since you're going to the trouble to ask for comments. Perhaps just looking for reinforcement of your inclination? Whatever, one thing is certain--the wife should get the whambamthankyouma'am orgasm(s) of her life from your hottt mushroom-headed wang...!!!
Now a perhaps unnecessary word of advice: Since you don't know this couple personally and can't be sure in advance of the husband's possible real temperament, exercise caution....