Hi,
Just thought I would post my experience using a sliding pot for the hi hat controller(
http://www.maplin.co.uk/Module.aspx?ModuleNo=2215). I used a 100k linear potentiometer fixed to an aacoustic hi hat stand with the trigger IO, it worked but not satisfactorily. I spent a lot of time tweaking the module and BFD2 and whilst i got it pretty close I found that it was not particularily smooth in transitions through the hi hat close to open. I am not saying that if more time was spent tweaking and setting it up i may have been able to get further improvement. I have now bought a second hand FD-6 for £22 (GBP) and I am very pleased with the result, I could use it with an acoustic stand but this would mean cutting bits of my pearl HH stand and I am not sure i want to do this.
I now get a smooth transition between closed, 1/4, 1/2 , 3/4 and full HH sounds. I did need to configure BFD as per the instructions in this thread
http://www.vdrums.com/forum/showthread.php?t=45034, and then I set up what midi CC the various sounds are within BFD.
Finally I can say that I am happy with the Trigger IO Hi Hat, not exactly like an acoustic one of course but I feel it is as close as I am going to get.
Hope that helps someone cause I know how frustrating I found it.