Como is probably the best 'knock off" line of engines in the history of of this hobby. They were built by Super Tigre and are just as good as the name brand Super Tigres. While I haven't personally operated a .90, my experience with other Como's was nothing short of excellent. We all hate to see an engine be "punished, and abused" through misuse. Nobody made more durable engines then Super Tigre, before they were built in China when quality slipped. It's always hard to recommend a particular engine for a particular airplane without knowing many details about the application, but if the original builder set it up for a OS.90 I would expect the Como to be an appropriate replacement.