Ken Pearlman is a fine player, Howie Burson is a fine player. Both play Celtic tunes (among others) on the five-string using melodic clawhammer right hand and some very intricate and accomplished left hand techniques. I've been using three-finger melodic style for whatever I play (mostly Celtic) for over 30 years. In my opinion, "the Tune rules" and it doesn't matter how you get to the notes.

In Ireland, many of the instruments played at sessions are not Irish by origin: synthesizer, hammered dulcimer, banjo. If you like the tunes enough to learn them and to get the feel of how they are presented in the Celtic idioms, that's what counts most. If you want your instrument to sound like a tenor banjo, I suggest you buy a tenor banjo.