i have an Xdrive2. Bought for $195 at Storage Studio, SLS. i put a 40GB fujitsu inside.
Pros: Portable, lighter than laptop. Cheap solutiuon.
Cons:
1. No verification. This is very dangerous. i also feel like a gamble when i delete my CF card after copying. This is a very impt factor. i suggest unless low price is major consideration, look elsewhere. If not, i can sell you mine and i go upgrade.
2. Poor battery life. Lasts for max 2-4 full 1GB transfers. In 10D, RAW mode, you're looking at about ~600+ max, with 2 full 1GB cards and a flat XDrive battery.
3. Unstable. Cannot move or knock the unit around when copying. ie, cannot start e copy, put in the bag and walk off. The copy will abort, and you will think it copied OK, bcoz when you take it out, it has auto-offed.
i get around the insecurity in two ways. 1. The approx copying time, should be about 30minutes for 1GB. If it's much shorter, something is wrong. i also copy twice if its impt data, but that will mean i run out of batt faster.
i think XDrive might be better than as a second backup.
Can try Nixvue or Portabin. Note: if you're going into the $800+ range, after spare batt, casings, and what not, might as well consider a second hand laptop. Laptop is still by far e best solution.
Another good solution for wedding. Get another 1GB. On a 10D, shooting at best res in jpg, i'm looking at 600-1200 pics, depending on ISO and compression. That's about 15-30 rolls, in film terms. You also get a backup CF if one fails. For my wedding coverage, i'm using 2 1GB microdrives, 1 Xdrive2, and i'll beg/borrow/steal a laptop.