Shame on whoever would scoff at such a well respected Mod.
Check access times on them. Although it may seem like a good deal, waiting for 30min to get your data off or on it is a real pain.
I know that some drives have compatibility issue, mind you those have mostly been worked out by now, and be sure you get one that's USB2.0 at least. Anything less, and you'll be old and gray before the data transfer is complete.