I’ve had 3 or 4 customers throughout the years with these things and it’s been sometime since I’ve seen or worked on one.
That said, if you pick one up, make sure you get all the sprockets you will need. The 428 sprockets for these are difficult to find and you’ll never find one trackside.
The early engines were notoriously hard on clutches, and although I believe it was fixed, I’d make sure you have whatever the updated clutch may have been.
Temperature, like all rotaries this things goal in life is to freeze the intake side and melt the exhaust side. You’ll likely never want for more power, but that power comes at a trade off, which is heat management. I remember seeing pictures of these things at night races with the headers glowing. Looked super cool. The not so cool part is if the engine overheats, you run the risk of warping apex seals, and those are rather expensive. If you stick the largest radiator you can on it, and don’t go crazy with the RPM (I recall they wanted to be under 12,000) You should be good.
There was two models at the time I dealt with them. One had an electric starter, the other one used an outboard. The outboard one was our personal favorite because the onboard starter often struggled to crank the engine. The solution was running an additional battery in series. So if the convenience isn’t a concern, the outboard is a less complex and lighter solution.
And the other issue with these things, was parts availability and pricing. It’s hard to promote an engine package in the US when it doesn’t have a race series it can run in, affordable parts, well understood technology by the users, or a distributor that’s familiar with the Karting industry.