I felt this fit better in the Cloner sub-section so I moved it.
I bought a Cloner with dual extruders right when it came out. I fought with the alignment between the 2 extruders and currently have the second one removed. It's kinda a pain in the ass.
That being said, it is my daily printer ATM. Here are my views on it:
1) The flanged bearings on the end of the shafts for the y belts are not high enough quality as they have a tenancy to fail. I replaced the 2 front ones with ceramic units and they are working fine. Problem is they have been discontinued on Amazon. The rear ones make a cracking sound sometimes but have not actually caused any issues.
2) I have issues with the bed staying at the correct height. After removing a print from the bed, I have to remember to pull up on it to get the correct first layer height on the next print. I have learned to deal with it. There is probably a simple solution to it but I just deal with it.
3) In my opinion, the Y stepper is undersized for the carriage load. I kept having missed steps until upsizing the stepper.
4) The rigidity of the frame is great. I have never had to realign anything.
5) Once you get it setup correctly, it's a good workhorse as long as you learn to work around the above shortcomings as I have.
6) I would not recommend purchasing the dual extruder unless you are prepared to mess with it a lot or have experience with dual extruder setups. It may just be me, but I found it too finicky. It is however a good way to get the spare parts.
Would I buy it again? Yes, I think I would but only if planning to use it in single extruder mode. I plan to mess with it again sometime to see if I can get the second one working correctly. If I wanted dual from the start, I would just mod a FT-5.