The problem is that the heat the rheostats produce when they are throttling the fans down is what melts the wimpier controllers and limits the PCB to 4 channels. Anyone foolish enough to buy a $40+ fan controller deserves the misery they get. Even that Sunbeam controller is only good for 4 fans. If you need to control more than 4 fans then you did not setup or modify your case properly. Excellent airflow can be had with 1 intake and 1 exhaust fan......
Intel E6300/Nouctua NH-9U w/dual 92mm Panaflos
XFX 680i LT
Patriot PC2-6400 2X2GB LL
2 X BFG 8800GTX in SLI
Enermax Revolution 620W PSU
ASUS 24X DVD/Seagate 250GB SATA 2/THermaltake A90/Windows 7 Ultimate 64