I too used a GG device, though not the Ithaka, that one was a big bigger than I wanted on my device. Here is a bit of my experience:
The GG Penelope V1: One of the first generation of rebuildables that wasn't a Genesis. I didn't care for gennies at all...which lead me to find the Penelope. It was a fantastic device for me, in fact it's still sitting on my desk in an old repurposed ashtray. Like all GG devices, they're manufactured by one man in Greece. They're done in limited runs, so they're hard to get ahold of, and the price is about on par with everything else in the genre. Replacement parts are tough to come by, unless you get lucky and need apiece that is still in stock from the last run.
As yankee said, the non-resistance wire takes a bit of getting used to, but it does make zeroing in the ohms a bit easier...but that's not really that big of a deal.
The GG Penelope V3: I mostly bought this one because I liked the other one, and wanted a second that wasn't identical to my first...man was I in for a surprise. The V3 has the Resistance-Wire-Only upgrade built into it. While I enjoyed using it, it just wasn't what I wanted. The small profile of the tank made the working area for the coil quite tiny as well. It also seemed to gunk up faster than anything else I own.
One feature that I loved about the Penelope's was the liquid control. You could close down the atty from the tank and it wouldn't feed the coil. If you were going to, say, build it and let it sit on your desk until your other atty was ready for a rotation, then you could do that without worrying. With my current devices, it's relatively unnecessary, so that feature doesn't matter much to me right now.
Kayfun Lite + V2: Man, what a mouth full. I have one of these and a Russian 91%. For all intents and purposes, they're the same device. Most of the parts are interchangeable, and they vape almost exactly the same. (The Russian and the Kayfun have air-control screws in different places. The Kayfun is fairly easy to build and vapes like a champ. It has a chimney down the center that houses your coil and keeps the juice out, except for two little grooves that go below to feed the wick. The air channel has a little screw that lets you open it up or close it down to your liking.
The best part about the Kayfun is that it's fairly popular here abouts, and you can find replacement parts fairly easily with a google search. I broke my clear center tank and one of the end tanks...(Don't ask...long story) ...and I found parts in stock and had them within a week. In the meanwhile, I had substituted parts from my Russian to keep my Kayfun working...it looked like sin, but it worked great.
Anyhow, here are my recommendations, in no particular order:
Get verified for the ECF classifieds.
Browse them to see what looks good to you. You can get decent attys from there for a bit cheaper than retail if you keep your eyes out.
Check out the Kayfun Lite + or the Russian 91%.
Good luck, Hope this helps,
-X