I can't comment from an experience perspective, but in case you didn't know, Scarab have these documents with tons of the theoretical numbers. Obviously they are always a little ambitious, but I found them fairly close to reality in my experience. But you do need to account for things like extra passengers and such. Their numbers are a little optimistic.
Page 11 for the 255.
https://www.scarabjetboats.com/uploads/2022/12/Scarab-Product-Information-Guide-2023_1.pdf
I know superchargers are famous for burning more fuel... but in my experience once again using the 230 engines, if you drive at optimal cruising speeds, the gas difference is negligeable. I own a Sea-Doo GTX 230 with the supercharger. When I drive it in eco mode over long distances (56 km/h), I get the same range as naturally aspirated Sea-Doos with me. In fact, if you look at that chart and compare at 30 mph, the fuel burn rate for the 170s and 230s is essentially the same. The 300 on the other hand....... lol. Presumably because of the higher compression ratio, design, etc. that one DOES burn more fuel even at lower speeds.
I also realize that superchargers are practically a religion, but the newer so called "maintenance free superchargers" do have minimal work required. Especially for people like yourself that rarely work it hard or drive at higher speeds with heavy accelerations and such. The supercharger is supposed to be checked every few years including a slip check. That's about it. If it does wear out, then Scarab/Rotax wants you to buy a new one... but third party companies CAN rebuild them if needed. Again, for yourself, they would probably last way longer than a few years. The intercoolers require little to no maintenance. Even in salt water, to my knowledge, the only thing you have eto do is flush the exhaust system. But I'm a fresh water guy, maybe I'm wrong.
In any case, I'm not trying to tell you to buy a supercharged motor or not. Just making sure you have all the info. I own a Scarab 165 naturally aspirated for similar reasons. I don't go fast with it. It's a "family boat" (small family of 3). So there was no point in getting a supercharged boat. But for the Sea-Doo, I do like having that extra HP when I "need it". Typically on group rides when of course, there's always someone leading faster than anticipated or you need to catch up to a group and such. I find the 230 a really good balance since it also uses regular gas only. Save on that front too.
