Well, the fretlesses I've enjoyed in the past were fretless StingRays (single H). I always wanted to approximate that sound, but have a lo mid control. So naturally the Bongo Hp was my best option to get what I wanted.
I so badly want a fretless now in fact I was watching DT play Peruvian skies at the festival in london and JM was using a fretless bongo to my surprise.