It is the FS-VX. I did a google search to see if anyone else modded it and found this:
http://shoryuken.com/f177/new-hori-...-v3-ps3-thread-207601/index4.html#post9774894
Did my mod pretty much the same. Desoldered the wires from the button PCB, then stripped and soldered new wires to the old and used quick disconnects. Common ground daisy chain setup. The "main PCB" has all the buttons clearly marked too. 30mm standard buttons snap right in.
Took less than an hour to do, wasn't the cleanest job, but I was bored and found the stick used for 3000 yen and wanted to do a simple hands on project. The case size and six button layout is just right for me.
That being said, someone sold an Amazon VX-SE (the black one with Seimitsu parts) at a store here recently. I'm thinking of getting some Seimitsu colors I like and doing a color swap and plugs for the far right buttons. It's not that big and it looks very nice in person!