95% hand held even with the MP-E 65, although that did have a steep learning curve.
A tripod is much more a hindrance than a help for the vast majority of macro shots especially insects, bugs, spiders etc. Too slow and cumbersome to set up when doing anything approaching true macro. It's ok for flower portraits sometimes or if you have docile critters that aren't moving, then it can be nice for focus stacking, although many can do that hand held too.
I hope I don't offend any forum members that have replied to my topic. I'm just trying to be honest about my potential use.
I have come to realize that my personal shooting style is very minimalist. I often only take two lenses, a moderate wide and a short telephoto, on most outings. My lens choice is mostly related to shooting environment, but sometimes can be influenced by a particular type of shot that I am trying for.
While I already own a very sturdy tripod and monopod, they never get used. Not to mention my 70-200 F2.8 L - at almost 3 pounds it never makes it out of the house.
While I am sure the 180 L is a magnificent lens, at 2.4 pounds, I know I wouldn't use it much.
I realize that these factors will make macro shooting a bit more challenging for me, but I like some of the (at .45 macro) photos I've been able to take with my 24-105 F4 L.
Right now, I like the idea of a moderate telephoto - 100 2.8 (L or non L), as my "style" will require that the lens often be used for more than just macro.
Any more thoughts?
As for what subjects, I suppose it will be a bit of everything.
Handheld macro is like handheld long lens shooting. Both can be done with excellent result. But if it's possible to use a tripod, the result will be even better.