To me, mobility is no problem and I like the challenge of having to creep through the grass to get a full frame shot of that timid insect, but I'm aware that some people don't enjoy getting all close and personal, and for that, a 150mm or something is probably better.
I have managed to capture many insects quite effectively with my Siggy 105mm. Here are a few examples;
No one can ever make your decision for you, but I highly rate this lens.
Nick
