I have big hands - the 6 fits me great.
I also really like the 4, even though the handle is smaller, it's still usable -- unless your hands are really cold and getting stiff.
As for the person who said a 4 with a 6 handle would be horrible, that particular model is called the Ontario TAK -- and it's a phenomenal tool, it's just not covered by the ESEE warranty. (yes, I'm one of those who keep hoping Jeff will relent and agree to build a 4" blade with full sized handle one of these days)
I love my TAK for day hiking, car camping, & food prep stuff, but when I'm out and about on the property or building a camp, I tend to carry an izzy 2 and my 6 to cover all my bases. (or the izzy 2 & Junglas)