You forgot to add the other 26 pins including the 8 analogs.
I got a Nano, I did still back the DUO up. The papilio has the wishbone and libraries that make it easier than VHDL or Verilog for just using the FPGA as glue logic. Also I got it because I want a Spartan based FPGA, I have 3 Altera ones so far and the combination of an ATMega32 with the xilinx well it got my interest. Of course you can still do VHDL or Verilog.
Have not worked with the Xilinx toolchain nor download it (I hear is pretty big so I might need to add a drive but I have to anyways since i'm always on the border of running out of space)
Another thing is that the papilio has a big enough community, not crazy big but not so small that gets stale soon. Also it's mature as in most of the toolchain is already in place, the papilio has a lot of examples for the ZPUino with the DUO that soft core gets replaced with the ATMega32. One thing about Altera is that their IPs are closely tied to the NIOS II, I know they make FPGA/SoC chips and might eventually get one of those too.
Anyways, the price is right, SRAM instead of SDRAM is a plus, and depends how they wire things up having the Arduino shields heavy lifting offloaded to the FPGA makes sense to me.
To me the FPGA acts like glue to hardware, so it's kind of an electronic duct tape that allows you access to hardware not intended for your specific platform.
So to me, the price is good, the community is growing and supportive, they proven themselves already with their previous papilios and I really want to expand my FPGA knowledge beyond Altera. Don't get me wrong, I love what Altera offers and how much documentation there is online, so it's time for me to expand my horizon.