I've just received my CopyNES a few days ago, and I've had the chance to fix a reasonable handful of bugs in the Win32 client code - for example, Bankwatch now works correctly.
I've also successfully made a CNROM devcart, using two 32KB SRAMs and a pair of slide switches (one for mirroring, one for PRG write protection), and I've added support for it to CopyNESW. A note to anyone who might want to make one of these: the PRG ROM normally ties /CE to ground and /OE to the chip select signal - if you drop in a 62256, (along with rerouting A14 from pin 27 to pin 1 and connecting R/W to pin 27), these
must be switched around - I neglected to do so, and spent several hours wondering why a bunch of RAM was seemingly corrupted ($8000-$87FF [$0000-$07FF], $A000-$A007 [$2000-$2007], $C000-$C017 [$4000-$4017], and a few others for the CopyNES port chip).
As always, the latest software can be found at
http://www.qmtpro.com/~nes/copynes/