I have a bias for the Universal hub. It can be built with fittings and without. My handle on Thingiverse is Qube3Bot. If you look over my designs, you will find most designs by typing in "B2B" in the search box. Here is some more info - http://www.print3dforum.com/showthre...-Universal-Hub

PLA prints work just as well as ABS. The chamber with the nozzles has a cooling fan. The heat buildup in the enclosed volume is minimal.

One word of caution on the fittings - fittings do not tolerate rotation of the bowden tube. This cuts a groove in the bowden tube. This could mean that the release mechanism doesn't work. Considering you have to twist the nozzle to remove it, the groove will happened.