Love the Spark!
Hi Tash
The Spark is so much fun to throw around, jump, 180's, bronco's etc.
To compare to one of the bigger, heavier and more power jetskis would be similar to comparing riding a BMX bike vs a heavy street cruiser or racing bike. Do you want something nimble and fun or something to sit back on and cruise?
If you go on the river and running for speed you'll match the other skis for the first 50m then they'll leave you behind. (Spark top speed is 80km/h vs >100km/h for the bigger skis.) For acceleration though and punch from a standing start the Spark is the best

Be warned though - a couple of hours riding a Spark and throwing it around aggressively will leave your arms and legs worn out, aching for a rest, but secretly waiting for tomorrow to do it all again!
You'll definitely want 90hp - either stock or from a 60hp plus tune.
IBR is really nice to have, especially at the boat ramp or sitting in the middle of the lake chatting to mates. Don't know that I've ever needed the shorter stopping distance from speed but it is fun to try it out

(make sure you hang on.....)
2 seater or 3 seater - buggerall difference. If riding 2-up definitely get the 3 seater though.
Go on - buy a Spark!!!!
where is Australia are you guys from? I'm Sydney northern beaches.