I recently picked up one of the Neoflash flashcards for PC-Engine/Turbografx. I own a Laseractive with the NEC PAC, and was excited to try running more hucard games. Unfortunately, I discovered that there's a design flaw that prevents it running out of the box, even though they claim it works on all models of PCE.
There's a reset button on the card itself, I'm assuming because most PCEs don't have a reset button. However,
The PAC-N1/10 have a much more enclosed card slot than other PCEs! As a result, the reset switch gets caught on the top of the card slot and the button is held in, which prevents it from being able to run any games. I was too afraid to try taking the button off myself, but a friend helped me out and took it off for me - he said it was really easy. It works fine now, but if you're interested in buying one of these you'll have to keep in mind the fact that you'll have to do that in order to make it work.