There is nothing dodgy about Kevin Wilson effects. He is very communicative and helpful, I was impressed with his response time, and even more impressed with the wah itself - if I was a person who made absolute statements, I would say it's the 'best' bass wah by some way. But I don't make absolute statements...
To answer the 6v12 position question, this is the reply I got from Kevin when I asked the same thing before I bought mine:
Mark,
The 12 position has a higher range setting. You are able to dial in 5 additional higher Q settings and 6 additional lower Q settings if you take out the in between settings you'll actually be able to go 3 complete settings higher on the Q range and 2 lower Q settings on the 12 position. The others are in between values of the 6 position.
Thanks,
Kevin Wilson