Do you use
Porros
Roofs
both?
If you answered "both", what influences which you use for what?
Mostly roof though I have some porros.
Ergonomics.
I own both, but as an all-season birder and avid butterflier, I mostly use modern alpha roofs in full, 2/3 and folding pocket sizes because they (1) are smaller for any given objective size which makes them easier to pack or manage around the neck with other equipment while hiking, (2) hang better, (3) have closer focus, (4) have smooth focus in cold conditions. The only porros that I use regularly are the Pentax 6.5x21 Papilio, with their unique stereoscopic close focus.
--AP