I do not have any ash blown up in the cooking chamber the fan although a 25cfm doesn't blow all that hard.
I chose to pipe the air in from that far away because the amount of heat that radiates from the firebox is extreme so much that i have actually cooked on it like a griddle and fried eggs.
I went with the Stoker because i liked the ability to use multiple probes. Right now i use 2 pit probes one for controlling the fan and the other as a monitor on the other grate in the cooker, and i use 2 meat probes one for brisket and one for butts, but there is the ability to expand even more than that if i wanted to with the expanders that rocks sells with the same unit. I think you are limited by how many probes you can use with the guru.