We had one on our boat and it was great.
We would never consider one in an RV.
Fundamental difference: RV's use a simple gravity drain system that really aren't prone to failures. Boats more complicated pumping systems prone to blockages and failures.
Maybe if you boondock for weeks at a time.
With our current RV, we can easily go for a week without draining but usually we get full hookup for longer stays, so it's irrelevant for us. For shorter stays, you are moving and it's quick and easy to dump the tanks at a dump station (many truck stops or rest areas have them if you aren't staying at campgrounds).
With a boat, there are no full hook up slips and dumping overboard is limited to offshore. If full or broken, you have no toilet. With a composter, there is nothing to break and even when "full", you can still use it a few more times without any issues.
You do still need to dispose of the urine every 2-3 days (depends on the model, we had a natures head). In a marine setting, it's a lot easier to walk a sealed container to the bathhouse and dump it down the toilet compared to preping the boat to go out and then cruising over to the pump out dock only to find the pump out is broken.