ooh interesting stuff going on here for Spartan devices eh?  I need to check some of this out in my compiler as well.

The latest confirmed 50MHash/s on the lx150 - which codeset is that? the LX150_makomk directory?

and thats a lx150 or lx150t?

also, I see a testbench in there - do you have maybe a timing diagram of expected/correct outcome for those inputs?

not too familiar with ISE 13 myself or verilog for that matter - i use mostly vhdl, but it also looks like you left a chipscope core in the project file in the github

also looks like the ucf is set up to receive a 100MHz clock and I don't see any clock dividers in the code?

edit:
hrm... so it seems you are using chipscope to communicate with the chip? interesting, I havn't seen that before - you guys discuss that somewhere in this thread? what software are you using to talk through the chipscope objects?