yes, search is one of the problem for button based, but I have tried to have a good search function for both albums and singles in my software, even for button use, where I recently have added a free text search feature that search for all libries in one go.
Otherwise the main problem here, is the MameRoom cabinet style isn't good for that search function, because you really can't use a SMS style input, where you need a phone style layout (which would been easier). Instead I think a alphabet based onscreen is the way for the onscreen search which is supported in my software (you really NOT need up and down for that screen here).
But if you building it your self, you can allways change the controls used, since you never need to use the same layout they used. Even if you go touchscreen way, the cabinet would even been fit very fine.