It maxes out around the 43knot mark in a no wind no tide situation, which is approx 50mph. Before Wavehumper says, yes, the 4-stroke is slower than the 2-stroke opti, but not by much I don't think.
On a good day, I get around 1.6miles to the litre of fuel, a bad day is about 1.2miles to the litre with 8 people on board, and giving lots of throttle. I seem a average around 1.4litres to the mile though.
Being quite small, there is quite a bit of twist from the prop at higher revs, although this isn't obvious with the engine trimmed right out, when trimmed in in chop, you can feel the boat more keen to lean to port than normal, which is fine, just so long as you're ready for it
Other than that, I'm very happy with it - any attempted takeoffs are always ended with a very soft landing with very little 'crash', which worked out great last weekend when we were playing around in the swell at St Annes.