Why do you like the larger board? What shapes this preference? How much harder would it be to do surface tricks on a 142 vs a 138 if I went with the bigger board. I know they say for more pop etc the bigger board is better, but you lose some of the ability to turn it. Is a bigger board better for intermediate riders?
I like bigger boards because the increased surface area pops a little harder than a smaller board. Between a 138 and a 142, it's not a huge difference, but every little bit counts. As far as losing ability to turn it, think of it as a grand total of roughly 2 inches on the board, about 1 inch on either side. It's not going to drastically effect how the board handles. Think of it like this, ~1% extra swing weight and ~1% more effort for carving for ~5% more pop, it's worth it to me. A larger board planes up easier too, so its easier to get up, and less effort (drag) once riding.
The Ronix site and the ads for this Kai boot say it has the Intuition heat moldable liner
Sorry I assumed you were looking at the 2009 Kais. I could be wrong, but I do believe that the 2008s were the intuition liner, so again I apologize, you're right. I hate to recommend the 10s and have your toes crushed, but it's really hard to say without you trying them on. I'd rater have boots that were a little snug that I could pack out with heat molding that sloppy loose boots that are just too big.