I too have painted an MV with latex - my M342A2 in 4-color MERDC (winter, US & Europe, verdant) scheme.
Originally, I bought some Gillespie military-type paint (oil based) at the Dayton MVPA national last year. However, when I tried a few test spots, I felt (my opinion) that the "383" green was too shiny, and the "field drab" was too dark. So I went to a local paint store (Porter Paints) to see if there were other options.
They suggested the latex because it could be mixed to a VERY matte color. I had them mix some to match sample parts that I provided. After several attempts, we ended up with something that I was content with.
I like the fact that it can be brushed on. It allows me to work on the truck a little bit a time in managable steps. (a hood one day, a fender the next, etc. . . .) I didn't have to worry about preping the entire truck and then setting aside a day to shoot (spray) the whole thing. It allows for a little bit of instant gratification to keep you motivated. (Bjorn's philosophy, IIRC)
I actually like the look of the brushed on paint for the 4-color merdc (again, my opinion) - as it represents to me a field modification that was likely to be performed at the unit level (by the guys in the trenches, so to speak). To me, it is an authentic work truck. The color is also very FLAT.
Additionally, if the need for touch-up arises, it is very simple to open the can and brush on a little bit.
I would highly recommend a suitable and compatible primer. And obviously, it should go with out saying - proper prep work removing loose paint, rust, scale, dirt, etc!!!!!!!!!!. . . .
With the Porter brand paint, I also used their "Glyptex" (sp?) primer. It is a red oxide type primer that prevents rust, yet can be applied over just about anything, and is a good base for the latex top coat.
My intial results have been promising, although I admittedly don't have the long term results to announce yet. I just painted the majority of the truck back in late April and early May of this year (just in time for the journey to Aberdeen)