I don't like the looks of a rail. In fact, I deliberately sought out a P345 without a rail because it just looks better IMHO.
Recently, however I bought my first gun with a rail......an XD-45. I'm slowly warming up to the gun, but I still haven't decided if I'm going to mount anything on it yet.
BTW, I wish Ruger offered the P345 with a hi-cap mag like the XD. If they did, I would have bought one instead of the XD. The P345 is one of my all time favorite pistols.