My Shimano mega range wobbles. Posters here have said no problem. It has been no problem. There may even be a reason for the wobble, although I have not seen any agreement on that.
possibly bogus reasons include: making shifting easier, adjusting misalignment of the chainline.
2000 Montague CX, I do not recommend it, but still ride it.
Strida 3, I recommend it for rides < 10mi wo steep hills.
2006 Rowbike 720 Sport, I recommend it as an exercise bike.
1996 Birdy, Recommend.
Wieleder CARiBIKE (folding), decent frame.