Prints great, certainly worth building. It will print pretty much any material to around 3000x260x300 (I've lost some build volume because of the dual extruders, but it is worth it.)
Most of the printed parts were printed using PET-G. PET-G does have a bit of flex in it, but after a bit of experimenting, it seemed like the best material for the job. I've added mounts to add a plexiglass cover and will get around to putting one on at some point, although even without I am having a lot of success with ABS and Nylon.
Originally, it was built with a single Bowden extruder, then I went with 1x E3D Direct drive and 1x Bowden and finally went with 2x E3D Titan Direct drives which give excellent results. At the moment, the Titans are using two different steppers. Strangely, the small 1.8 degree stepper gives better results than the bigger 0.9 degree stepper (faster maybe?) so will be adding another 1.8 degree stepper. Parts cooling is through a Cobra style duct with dual fans.
It uses two power supplies, one 12V for most everything and a 24V which is for the heated bed. The heated bed power is switched through a solid state relay driven by a spare pin on the RAMPS 1.4 board (it was done this way so I could free up the heated bed output for the 2nd extruder).
Typically, I print at > 80mm/S. I was concerned that at high speeds the frame would flex (there is quite a lot of weight in the carriage) so have used 40mm Sorbathane hemispheres under each corner to absorb the movement.
I toyed with the idea of adding a 3rd stepper for the Z-Axis to eliminate any rocking action of the bed, but found by moving the Z drive steppers/screws closer to the fulcrum point of the bed, everything worked fine and I get nice prints - if it aint broken, don't fix it being the philosophy ;-)
It has a few Custom parts:Dual Titan Carriage, Fan Duct, Panel Mount, PSU brackets, Spool Holder, Glass Clamps etc.. Some of them may not be very elegant, but they work, so if anyone wants the files, I will make them available.