In my 50+ years of riding, and (oh, let's see ... haven't figured it lately) 38 years of lane sharing on all roads where it is possible I've never had an accident and only a couple of close calls when doing it. In fact in three instances it has saved me from involvement in accidents that would have been very bad, if not fatal! Most of the time cars will try to give me more room even when I don't need it, and I always try to acknowledge their efforts with a friendly wave. Another aspect of it is I try to make drivers aware of problems with their cars, such as a low tire or brake lights out, and it is always appreciated. I have waved cars into my lane, usually dropping back to make sure the car behind me doesn't fill the slot I've cleared, then splitting past them, and invariably get a most enthusiastic wave of thanks. The point is lane sharing (careful use of words here) means being part of traffic, not separate from it, as many motorcyclists seem to assume.
One memorable incident comes to mind -- on the 10 fwy during "rush hour", there was an accident about a mile ahead that stopped traffic almost completely, and as I was splitting came up next to a LEO car and offered to give him a ride to the scene, which he declined (he was alone in the car), but gave me his walkie talkie and asked if I would be willing to give him a report of the accident and injuries, which I agreed to do. When I got there I reported back on the license numbers, position in lanes, extent of injuries, and condition of the lanes not directly affected. Fortunately there were only minor injuries, most notably a scalp laceration that was not deep but bleeding copiously, and I calmed her down while holding a handkercheif against it until an ambulance arrived. I still get Christmas cards from her, and got a commendation from the police.
Lane sharing, if done properly, is safer than sitting in traffic, and there is no doubt in my mind that it has made me a better rider by teaching the finer points of reading traffic and deadly accurate control inputs: an inch off from your intended path can be a disaster! Needless to say, I voted for legalization.