I use gaiters a lot, they are essential for my type of hiking! Mine are Rab and they work fine but I've never noticed if they do a large calf model?
If I didn't wear gaiters then my rain skirt wouldn't work properly, I'd just end up with wet feet. And I really like to have them on when having to walk through wet grass and other wet vegetation, especially first thing in the morning. Again, if I didn't wear them I'd still have wet feet and I personally don't like wet feet!
Mind you I've always felt that gaiters need a complete design makeover, they are such clumsy things to start with. I'd prefer to buy a thin lightweight soft pair designed to be worn under my walking trousers, not on the outside. Unfortunately, as far as I know they don't exist.
I've always told myself that one day I'll get my wifes friend to sow me a pair but so far Ive never got around to it.