Mr. Barrymore,
As you point out, people are different heights in the real world, why not in the model world as well?
But, to me, the real problem is not 1:32 vs 1:35, it's that the manufacturers do not use a common measure....even though you'd think they would. For example, I ordered figures from both Kellerkind and Tommy's War. Both are really excellent sculptors and makers of figures that will work well with WWI planes and dioramas. I hate to tell you that, in some cases, the Tommy's War figures are almost a full head taller than the Kellerkind figures. And it's not just the height. The figures are all well proportioned so, size wise, one looks like an adult and the other looks like a child...with a moustache.
I have quite a bunch of recently made and very well done figures by a range of manufacturers here and, based on my experience, if you're getting more than one, choose figures from the same product line.
FWIW, Red Lancers in PA is a good supplier. Chuck Robinson is a good guy, the prices are competitive and he ships pretty much the same day. IT's amazing in this day and age to find an independent hobby shop!
http://redlancers.com/HTH.
Cheers from NYC,
Michael