FWIW I had a mid length single fin 2+1 that I wound up selling at the end of last season...it was something like what you're talking about, but I found that I was in a no-man's land with that board; the worst of both worlds as DTC put it one time....it was 7'8"x21"x3"....too big to duck dive, too small to paddle fast as a longboard meant getting stuck
turtle rolling inside more than I would have on
a longboard....
shortboard with
duck diving you're back on the paddle right away so I'd get outside easier with that as well....so on the bigger days when that board came to life (needed to be about 3ft before it became special) I'd get frustrated and battered around inside more than I would have liked.....
catching waves was ok, but again, worst of both worlds, had to catch further inside than on a longer board, but the rocker and size of the board made catching later on bigger hard jacking days more difficult than on a shorter board with less tail volume, length and more rocker.....on the wave it was a star and loads of smooth carving fun, but in the end too many negatives outweighing the positives, last of which is though the smooth style of single fin surfing is admirable, the thruster fin setup innovation is a flat out better system and gives you more grip and ability to draw different lines which is reassuring on days when the
waves are hammering down......and your tail doesn't slide out on sharp angled drops......don't have to baby it through the bottom turn.
Last bit is that if I were you I'd look for a local shaper and tell him which wave and what time of year you want that board for.....the board I had worked really well in certain conditions, but definitely was not an all rounder, and it wasn't shaped for me or for where and what conditions I usually surf, so it didn't work out though it was one of the best boards I've owned to date.
In it's place I got the Byrne.....handles the same conditions that the single did, but has a wider range, paddles just as fast but is lighter, smaller, more rocker, can take waves later and is tuflite (f___ing strong!)... low tide reef tuff. And it's a thruster.