Jeff,
I'm fairly new (3 Ut summers) and I try to go to Grants anytime I can. Never measured but guessing at 400m across (but that's what I need as it forces me to jibe). Also, the water is really flat. My experience is when it's windy there's not a lot of fishermen but the wind will change to blow you at the ones that are out.
If you can get out for dawn patrols you're lucky as that's when the wind is best. I usually get there late afternoon just as the wind is dying down. Ken and Tom seem to get in a lot of dawn patrols. You may want to talk with them.
Ever been to Grants? If not ask for specific directions as it's easy to miss.