I and at least one other person on this board have the Jet J/P. I went through this process recently. 8" is better than 6" but sure as shootin' 8" wouldn't be wide enough either. 12" jointers ain't cheap unless you can bang into old iron and have the means to get a heavy jointer where it needs to go. I have a basement shop and a half-ton plus jointer wasn't going down the steps into it. When the Jet jointer/planer became available, the price, size and design rang my chimes:).I'm happy with my choice but it ain't all that cheap.
HTH
Curt