I haven't been able to look at a BK-5 yet, but for those thinking about a BK-7m instead, because of the flimsy keys issue, perhaps, if you already have a good feeling controller keyboard, you might STILL be better off with the BK-5, and have a two manual system (BK-5 is supposed to be very light weight) with the controller being the main controller, and the BK-5 being the 'extra' manual?

Some sounds are actually BETTER to play on quite lightweight keys (organs, woodwinds, solo synths etc), while others (pianos in particular) benefit from full or semi-full weight keybeds.

Perhaps a full 88 wood, or 76/73 full or semi-full weight controller and the BK-5 as the secondary keyboard would be a VERY flexible system..?