I've always been a fretless fan after I was turned onto the sound by Pino with Paul Young back in the '80s. I pulled the frets out of my 2nd bass to be able to sound like that, so I've been playing fretless almost since the beginning of my affair with the low end beast. With restraint where necessary, fretless will fit in just about anywhere, you can even slap them (although not overly recommended due to potential 'board damage and the sound isn't exactly right - if memory serves a manufacturer came out with a fretless with 'slap plates' back in the day; it didn't catch on). I've only ever seen Pete Stroud, who gave a session at the at the SE Bash last year, use fretless basses live and a lot of the time you can't tell. It's not all about mwah and slides, but they are there if you want/need them. As we all know, your average punter isn't too bass savvy.