Upgrading the CTC printer to Sailfish 7.6 is relatively straightforward. It's covered well in this video on youtube: https://youtu.be/Z_Y9tCpsn3E
After doing the upgrade I found that Slic3r output was printing way off to one side. I wasn't too baffled, since it did the same thing when I first got it and was using it with RepRap settings.
I tweaked the startup GCode to reset the home, and since I was messing with it anyway, I put (0,0) back in the front left of the printbed as I'm used to from RepRap rather than in the center.
The main key to it is that after homing - the CTC homes to MAX positions instead of RepRap's MIN positions, I use a G92 command to reset the current position to (270,150) (it's off the edge of the bed)
I've saved my config bundle and made it available on Pastebin here: http://pastebin.com/HQ2y6tiB
Before importing that, be sure to save your existing config off as your own bundle to preserve your current settings, you may not like everything I've done.
So how's the upgrade?
Meh. Certainly a little better. I don't know that print quality is any different. There is some mid-print control now. You can change temps and one or two other things mid print. But it's still a far cry from the awesomeness of Marlin on the RepRap.
The temperature control is still horrible. RepRap went to PID control a couple of years ago, it's unbelievable to me that Sailfish apparently still isn't using PID - the nozzle temps fly all over the place. I set 200, it flies up to 212 before coming back down, swings down to 193, crawls back up again. With Marlin/PID, I set 200, it goes to 200 and stays within half a degree for an entire print. Accurate temp control is very important for print quality
The CTC is still an acceptable printer for noodling around with. For dual-head it's a pretty good deal. However if I didn't need dual head (and I don't - 99% of the time) I'd go for one of the RepRap clones. There are a bunch of i3 Reprap clones on eBay for < $300.
I'm OK with the CTC right now but I am not sure I'd buy one again. It's not a BAD deal for the price, but this firmware, it's not good. Even the updated one is just less bad. My only problem with the i3 that I built was that the frame wasn't as sturdy as I'd wish. I should probably build a new printer around a new frame.