16 comes with 29" tubes and fixed chokes. They say they will open them, nothing about screw in chokes.

I'd consider a 12 RBL, but a friend related to me an absolute horror story regarding a new CSM model 21 he purchased. He won't be back. Neither will I.
Sometimes, a company doesn't get even a single chance with a new customer, if that customer talks to a former customer.

Best,
Ted