Anyone ever replaced the drive in a G-Drive?

I need a new external hard drive, and I really like the G-drive cases. However, they don't sell just the enclosures. So I'm thinking about picking up the smallest one I can find, either a G-Drive or G-Drive Mini, I haven't decided yet (probably the Mini though), and then at some point replacing the drive myself with a larger capacity one.

It looks that I can get an 80GB G-Drive or a 40GB G-Drive mini for about $100. Then, if I got the full-size one, I could put 400GB in there for $100, or if I got the mini I could do 160GB for roughly the same amount. Which either way would be a heck of a lot cheaper than buying it right from G-Drive.

My question is: what type of interface is on the inside of those cases? I can't determine if it's PATA or SATA. Has anyone ever replaced their G-Drive before? I presume it just has a few screws, like any other hard drive enclosure. I would appreciate any insight, or recommendations for cases that look like the G-Drive and match their build quality.

Update: I've purchased a 40GB G-Drive mini from Apple.com because they were on clearance for $79.95. From my research in G-Tech's product spec PDF, I am assuming the G-Drives all use SATA. It doesn't say specifically that the G-Drive Mini does, but the G-RAID Mini uses SATA and it's basically the same enclosure. I found a 160GB notebook drive for $105 too so I'm good to go

As long as I can actually replace the drive...I assume I can.

Yeah, I don't really care about the G-Drive warranty. The hard drive I put in it has a warranty on it.

I decided to go with the smaller one because I mostly use these things for storage on the go. They don't sit on my desk (I have a 1.7TB file server for home storage), and carrying around the larger 3.5" ones with their power supply is quite a hassle. Most 2.5" enclosures are barely larger than an iPod, and are powered from the USB bus. If this works out, I'll be fairly happy; a 160GB 2.5" bus-powered portable drive in one of the best enclosures you can buy. Of course, the one downside to all this is the Western Digital hard drive (the Seagates I found were too expensive), but if it dies after a year (like most of my WD hard drives -- usually a couple months after the measly 1-year warranty is up), I'll just upgrade to a bigger and better drive.