It was sent back within 30 days of purchase (1989 IIRC) to fix weak ejection, a gritty trigger and dismal accuracy. It came back well-repaired on those three counts, to say the least.
Then about five years ago I sent the slide to Novak's for installation of their tritium sites, which were a factory option a few years after I purchased this one. This was just before I took a Rob Pincus course, where I was the only one sporting a 3rd generation Smith. As expected, Rob gave me a bit of grief over my selection of firearms but the 5906 performed admirably.
I'm thinking about a Sparks 55-BN for it, even though I have no plans to carry it. How much sense does that make?