It depends on how you define high mileage.
For collectibility and increased value it had better be low. The lower the better. There still new zero mile crated RC51 bikes out there.
For avg condition and use, it is not a huge amount of miles. The RC51 has been a statement bike for many people. So many bikes are low mileage. It skews the avg miles to even lower than sportbikes in general (which is lower to start with than the avg bike of other styles). I'd say 25K or so miles is an easy to find avg. Many bikes will be higher, many other bikes lower.
For durability, it is a notably higher number. A few bikes have worn oval (the cylinder head) and started smoking with higher mileage (50K miles) as reported here. OTOH, there are many more high mileage (>40k miles) RC51s out there working fine and well (wrt the fact that not a lot of RC51s have actually gone 50k miles or more and are still around, yet alone reported on the internet at discussed). I'd imagine the expectation for 200k miles reliable should easily be in reach (well maintained) and it could easily double. Engine reliability has long been a strong point in japanese bikes and japanese sportbikes.
All three are unique yet apply. Decide where you want to fall. Prices change hugely depending on which definition you apply.
Last edited by kwtoxman; 10-24-2016 at 11:03 AM.