There is absolutely no reason not to get your updates from Garret. Great communication and great service (he obviously doesn't work for Pioneer), an excellent product, at a much lower price than updating with the Pioneer DVD.
This is the second year I have gone through Garret to do my update, so he has earned my repeat business. The cost to do a basic upgrade (since I got my 60g unlocked hard drive last year from him when I upgraded from Z1 maps and software to Z3) is way less than from Pioneer. That reduced cost makes it economically reasonable to update every year. And he will do the update and save all of your songs and personal information that you have loaded on the hard drive.
The turn around time is phenomenal. If you're like me, you don't like to be without a fully functioning unit for more than a few days. Garret got my hard drive on a Tuesday and, literally, within a couple of hours had it back in the mail. That meant from taking it out of the car on Monday to reinstalling it on Thursday took a total of four days (I, like Garret, live in Texas--your times may vary, but probably not by much depending on how you mail the hard drive to him).
If he's still providing this great service for the Z community next year I fully intend to update through him again.