I own a Europa TriGear XS with the Rotax 914 engine. The 914 is basically a turbocharged 80 hp 912 that will give 100hp in "normal" usage but with a max of 115hp for a max of 5 minutes when needed
With 2 up and full tanks the take off run is well under 250 metres on dry grass (never accurately measured it) WITHOUT using the extra 15 hp, the "book" says 150meters or so - but that is on a hard runway.
I do have a CS Prop (Arplast) which gives superb performance and economy - cruise at 110 knots on about 12-13 lph. That's about 45 mpg in real money
The monowheel is more slippery through the air and should give about an extra 5 knots over the trigear all other things being equal. HOWEVER ground handling is, how shall I put it, "interesting" with the monowheel in any sort of significant cross wind.
I have personally never flown a monowheel but been a PAX in one and to say the landing roll was "squirelly" is to defame squirrels - rudder inputs were close to bicycle riding in a low gear up a steep hill - fast and firm.
Those who fly the monowheel tend to love them - they are cheap to fly, have excellent performance and handling as an air-craft, as a land-craft they are not the easiest in the world.
I like my trigear even though the Europa traditionalists refer to them as he "one's with the training wheels" - at least the TriGear doesn't have those silly little baby stabilisers.
Summary - I wouldn't recommend the monowheel for a newbie PPL with no tail dragger experience - a ground loop (or worse) waiting to happen.