We were at I-Drive over spring break last April and stayed in Building 7.
We did the Disney visit and was very grateful we rented a car. It made getting around carefree. I think the statement that parking is a nightmare is a bit overstated as long as you are able bodied and can walk.
It was annoying to come back after 10pm and not get a parking space near our building. What that meant was we parked near the Pizza Hut and small pool near the neighboring (non-HGVC) parking structure and walked a few minutes. After walking all over the Disney parks, walking a bit more to the unit wasn't a big deal...just not convienent. On at least one occasion I dropped off our carload in front of the building, then drove on and parked.
Oh, we were very impressed by the size and selection of the Publix grocery store!!!
I think if I were going to go to visit Sea World and other non-Disney attractions I might stay at the HGVC Sea World location...but it's not a big deal either way.
We enjoyed our stay at I-Drive very much, even if they wouldn't let me swim in the lake.