You really don't notice that. Prop speeds are substantially lower.
I have no real experience with the O-200, maybe a hundred or so hours with Lycomings before the Rotax. I have been flying a Rotax 912ULS in an RV-12 for the past 5 years. During that time, my engine "problems" have consisted of one instance of a spark plug boot coming loose, caught during run-up (10 minutes to de-cowl and fix, $5 to replace that boot at the next annual). I've probably added a grand total of a pint or so of oil between changes during that time... it just does not burn oil. Winter and hot starts are a complete non-event. Burns 91 octane MOGAS, or AVGAS if necessary.
Maintenance during the annual CI hasn't been bad. Fuel lines had to be replaced during the first annual - the original rubber hoses are a 5-year item. I spent a little extra for firesleeved conductive Teflon hoses, which I'll never need to replace again. The coolant lines are still a 5-year item, so there's a few extra hours every 5 years. I bought a gallon of coolant (automotive antifreeze) that will probably last until I die. Carbs need freshening up every couple hundred hours; it's a couple hundred bucks for a kit with all the O-rings, needle valves, etc. needed. Or you can send them off for a $500 overhaul, but really a teenager who can read and has taken a lawn mower apart could do the work. New plugs are under $3 each, and you can buy them anywhere. During all of the maintenance I've done, I have found that if you follow the Rotax service manual to the letter, everything just works - perfectly, the first time. No "tweaking" required.
Operationally, the engine has been a joy. No drama, no hassle. Starts are effortless and reliable. No priming, no manual mixture control, no carb heat. Good cabin heat in winter. It's nice and smooth. The tach reads high compared to what you're used to seeing -- takes a couple of flights to get used to that. I cruise between 5000 and 5300 RPM usually. That means a prop speed of roughly 2000 - 2200 RPM.
TBO is 2,000 hours, and I get the sense it will make it there with no problem. Unlike a Conti or Lycoming, my understanding is that during a major overhaul the crankshaft will get replaced, but not the cylinders. I don't know, with 450 hours on the engine I doubt I'll need to worry about it.
There are tens of thousands of Rotax engines flying, and they have been in the field for decades. This is not new and exotic technology. Rotax has been very, very attentive to the engines, with tons of freely available documentation (light and heavy repair manuals, service instructions, etc). and changes over the years to improve reliability and longevity.
