These Pianos aren’t completely different to Yamahas that are build for the US or european market. They should be maintained by any Pianotechnician without any problem. But thats not the only problem with grey market pianos. They often come from asian music schools wich mean they have been played A LOT even though they look pretty fine from the outside, so be aware of that. But surley you can have a lot of fun with one of these without any doubt. For around 3000$ you might get the best deal with a used Japnese. For this price its hard to get an equal US/european made upright. If you want to avoid grey market Yamahas i would be a bit careful buying any piano from the 70s/80s. The most grey market pianos i came across where from this era. Sorry for bad english.