Well they wrote to me as well asking what I was going to use them for. Told them I was testing them for 3D printer linear bearings. Never heard back.
My buddy Art customized and printed these for his i3. They work pretty well. http://www.thingiverse.com/thing:1653714
Interesting, I think I'll be going with a little different take on a similar idea when I make my bearing.
I know its late, i personally use a clone of an ultimaker 2, it printers very nicely I just had to swap out the z axis screw because it does not come with an acme lead screw. that did require a fresh upload of code though. I jump up from a geeetech rostock mini (revision 1) all I can say is never ever buy a printer from Geeetech. The only parts still stock are the upper and lower plates. It hobbled along to print itself parts until I got rc ball joints, e3dv6, and new carriers. I also quickly learned that you get what you pay for in linear bearings. I mean now it is fine but the print area was too small and forced me to curb my 3d printed brooklyn until i got my ultimaker clone running 100%. i have to say from pre lead screw change the prints were nice except for the slack in the old screw lead to layer waves. It is much quieter than the mini rostock due to its brass sliders instead of linear bearings. I can post test prints once I'm done modifying the firmware.