http://farm4.static.flickr.com/3404/3208760297_cc4ec507e9.jpg
While spending a little time and effort painting these little 1-72 blokes, it wasn't until I recieved my 1-72 sailors that I realised the soliders are in fact rather short, I would say that if the sailors (1-72) were 6' tall, then the soliders would be 5'5" which for my little diorama won't look right.

Don't know if I agree that it won't work. If you have the guys standing at attention next to each other in full formation, then it might not work well. But with varying postitions and difference stances and locations will soften the overall height difference.
Plus naturally there are height differences in people.

In 1/35th scale it happens a lot with injected figures and resin figures. You have to be aware of it and work with it but it can be done.

Also in terms of realism different heights is ideal, What i mean is that in real life we are not all the same height we vary, and a person's height didn't really have to much baring on them fighting .