Just got a taz 5 a few days ago. Been really impressed with them. I still don't have the bed fully level but the PEI surface has been wonderful compared to everything else i've ever used. it's like it's a completely different kind of machine. I looked at them for the same reason, open source but they really deliver on the actual product. my only complaint is one i'm going to fix myself if i can't find any other way. the LCD is bright at night when printing in the dark.

If you are around northern Colorado, they give tours of their place.