Can't help you on the how does it taste question but I'm sure there are more than a few subbies here who can.

I never understoon oral with condoms, the taste of the plastic must be worse than cum could be. The point I wanted to make was that there may be an alternative. To give oral but then let him cum on your face. Personally I'd rather cum on her face than in her mouth. There is something very attractive in a cum faced subbie. Its a male thing. Perhaps you (both) should watch some facial videos. If you go the facial route its a good start and allows you to taste a few drops without having the full load.

PS - You could wank him off then lick the cum up off his belly, that would allow you to have a little taste and some subbies like to do the clean up jobs.

But a girl's got to do what a girl's got to do so come what may blow jobs are a dirty job but it's got to be done !!