I believe most issues involve damage to the protective coating on the titanium cylinder. Brake cleaners and the like, as well as ammonia products appear to be harmful. I use Hoppes or Shooters Choice and bronze brushes and never had any problems. I avoid any abrasives on the outside of the cylinder. These guns are not fragile, just super cool. I am pretty sure the M&P 340 with stainless cylinder was introduced because people did not follow instructions with the 340PD. Keep your gun. The 2oz. it saves is worth it.

Links from a couple of forums--

cleaning a titanium cylinder

Use of solvents on titanium, scandium or alloy revolvers - THR