I "filter" at intersections and "lane share" (that's the legal term in CA) at slow speeds. We have many times, on freeways with 65 mph speed limits, and sometimes on the ones with 70 mph limits, that traffic is dead stopped for long periods. I "filter" through the stopped traffic, and "Lane share" when it's just crawling. My personal limit is around 20mph. CA Guidelines (not laws) suggest that the rider should not be going more than 5mph faster than the cars or truck they are passing between, so If traffic is moving at 15, I'm doing 20 and that's enough for me. Many times, I have to pull into a lane to let other, faster, riders go by me. My feeling is if they want to piss-off every cager, I'm not going to get in their way, but I won't participate in high speed lane splitting.
As I've said on other threads, I won't be sitting, stopped, behind a black smoke belching diesel pickup, unless I'm in a cage with a HEPA cabin air filter, on the A/C system.
This is just my opinion on what I see as "right" for me. I recognize all other riders' and cagers' opinion.