Hi Dydst welcome to ECF,
I think if size is a concern at all for u go with the 650 Twist. IMO the 1000 Twist seems a little to big to carry around. I take my 650 Twist out every day and it last me. It won't last all day (7am-12pm) but it will last me the time Im away from the house. I always have 2 EGO batteries with me anyway so it doesn't bother me to have less mah power. hope this helps.
Thanks guys! I decided to go with the 650; maybe I'll get a 1000 down the road.