I use a G15 (v1, 18 keys), and LOVE it and would never go back. I started off small and expanded. First was 3 keys, 1 DPS, 1 healing and 1 misc. I mapped them to G13-G15. Simple easy to reach. They really haven't changed in 2-3 years. Since I now have Macs, I picked keys that can move easly across mixed platforms. I settled on Numkey 1-9 mapped to G1-3, 7-9, 13-15, then CTRL-Numkey 1-9 mapped to the others.

Now I have keys for ground mount, flying mount. vent push-to-talk. I have 6 keys that I can use for pretty much anything. I have 2 keys for move alts forward and move alts backward.2 keys for Jamba-Use item bar, 1 key for accept all macro and 1 key for buff (triggers smartbuff).

I love that I can see my chars stats. I like that I can see CPU and RAM usage, whispers that come in, vent info when someone talks, and BG stats. I like having controls for volume, media player and lighted keys. I just really like it all.

I don't use the 2nd or 3rd set of keys much, I made a script to type in "/script LeaveBG()" and "/script LeaveParty()", but don't use them much. Jamba-team disband works great and I don't do BGs much since WG. I am crossing my fingers that Jamba adds a Jamba-team LeaveBG so I can leave the other part off.

I wish WOW used G keys natively, but it probably won't ever happen, but you can just use modifiers with keys (use CTRL-SHIFT-A, CTRL-SHIFT-B, etc). But to have keys that you reach easily and can be used to do a lot.