There is evidence that people who are in type clubs typically have better safety records. In the Twin Cessna group, I think that would be due to the general culture pushing for more safety and the fact that someone who joins a type club is probably fairly safety conscious anyway. On the forums, we have lots of type-specific questions and discussions as well.
Probably true for type clubs that focus at least part of their time on flight training. I'm not picking on them, but the generic Cessna Pilots Assn has virtually zero to do with piloting and 100% to do with systems and mechanical knowledge of the type. This is not unexpected considering it's founder is a mechanic.
Comparatively if you attend certain coursework in say one of the Beech or as you mention, Twin Cessna organizations, there will probably be at least a discussion of flying technique or real flying with an instructor involved.
I haven't really found a Cessna Singles "pilot's" association that focuses on flying technique. Well, other than hunting down CFIs with a bejillion hours in Cessna spam cans.
Here's a fun side question: If you were designing a Cessna single-specific weekend course, what would you put in it for a curriculum?
One example I can think of is Doc's "load the back up with magazines" posts... How many people have flown their Cessna regularly at MGW or MGTOW (and in the latter case known they had to fly for X amount of time before they could land)?
Other possibilities:
Spins for the models that can do it legally?
Crazy pre-flight games looking for stuff pre-broken by a mechanic that are hard to spot?
Learn to change a tire?
Time in a rental that doesn't have a damn "no unimproved surfaces" clause in its insurance and a chance to actually land on gravel/grass?
Another event some type clubs do is having a few type experts go over your aircraft with a fine-toothed comb just as part and parcel of the event. Point out stuff you may have missed or didn't know about.
Seems like there's room in the Cessna single world for such things, but it'd be a labor of love, knowing how cheap most Cessna single drivers are. Dunno.