I have no other relationship with panstamp except being a "happy user", but I think it deserves a bigger community. Take a look. The SWAP stack is great, even if its all-HEX approach isn't the most user-readable one... If you can make a side-by-side comparison with DASH7, I'm interested.
It's still not entirely clear to me whether OpenTag (HayTag, what's the difference?) on an 8bit AVR (not arduino).