So, you are Alex Hixon?
Wellcome aboard!
Cheers! I'm glad to be here.
No, I am not Alex Hixon - I should have made that clearer! I reached out to Mister Hixon about his cards about six months ago and have heard nothing back. It seems as though he's gone off the grid (or this part of the net, at least) - hopefully he's alright.
The development page on Hixon's website was invaluable to getting my project off the ground although I went a slightly different route, opting to use the DS8925 chip from the original serial cards rather than something modern. Might as well put those old, plentiful chips to use. I also use the original modem port's housing for mounting the serial connector, which means you don't waste a PCI slot on a non-PCI device and gives the upgrade a stock-alike look.
I've sold about fifteen kits so far and people seem really happy with them, which is great to hear.