We used them too...booked in January for our mid July trip. I did get the insurance, and when Disney came out with the 5-for-3 deal we were then able to upgrade to the DLH from offsite without penalty and GAT was great about it. We were able to get our park tickets, character meal tickets and even our Sea World tickets through them at a discount as well (we spent a few days in San Diego too). I would definitely use them again. I booked online initially, called for the change/upgrade and didn't use the payment plan.
I will say though, that what they send you ticket wise is an electronic voucher and if you are staying onsite it is absolutely no big deal since you can get all of your character meal vouchers and park tickets when you check in at your hotel...but if you are staying off site you would have to wait in line to change it out at the park entrance. It was kind of a pain at Sea World to have to wait at guest services to get the actual tickets...worth it to get adults for kids prices and have it all already prepaid, but a pain nonetheless.