I have just started my quest for a dual extruder printer and decided on the HercuLein (https://github.com/eclsnowman/HercuLien). Eric Lein has done a wonderful job with his printer design. It will be a slow build as some of the parts are on the rather expensive side when you compare it to the Robo. I am using the Robo R1 to print all the printable parts. This allowed me to fine tune my filament profiles since all the parts I have printed so far are at 100% infill. I am finding that 100% infill changes the way you think about different slicing parameters and can be a real challenge. I am also printing multiple iterations of identical parts, changing filament types as I go along and comparing the results. Right now I am printing in PETG and ABS. After the ABS part cools I measure it against the PETG part and I have got both of those pretty much dialed in. The cooled ABS part is identical to the PETG part in every dimension. I am going to print a set in Taulman Alloy 910 and may play around with RIT dye. I have used RIT in the past with prints from Shapeways so we shall see how it goes with self-printed parts. I plan to continue to use my Robo for nearly all my printing as it will be some time before this project is completed. There is a lot of talented people contributing to the HercuLien and Eustathios Builders Google+ group. Their community seems as friendly and inviting as this one has been. I will update this thread whenever I get a chance to add to my project.