Bismuth has some disadvantages (supply/brittleness). But, barrel/gun/choke damage isn't one of them w/appropriate shells.
Lot's of folks would argue it's still the best option for old guns. It's nearly as soft as lead and not as abrasive as some of the matrix type nontoxics. Plus, there's gobs of slower/low pressure reloading data out there.
I'd shoot reasonable shells/loads w/absolutely no concerns, regardless of choke.