3" would raise the issue of type of tree, and likely root structure, and at 4" it gets a bit dicey, regardless, but the 2" - no problem (unless you don't wear hearing protection, in which case it'll be kind of noisy).
I've an
L3410 with standard FEL (yup, have toothbar, but it's not needed for this stuff), and when I was clearing my property had a heavy duty Woods 60" brush cutter. Now that things are cleared, I've a Woods 72" brush cutter, of medium duty capabilities.
Anyway, in the land clearing mode, I just put my GST tractor in a low gear, FWD, with the FEL lowered to a few feet off the ground. Heavy brush (in my case, wax myrtles, raspberry tangles), pine saplings, small oaks, sweet gums and the like were toppled, and the brush cutter osterized them. It could take a number of passes to get the debris down to coarse mulch, but by a year I could go over the area with the newer and only medium duty brush cutter, sans FEL, and just have a finely mulched base with "field grass" growing through.
Yup, 4" plus diameter trees met my Stihl chain saws, and DR
Chipper.