I use the RMS paints about 90% of the time. So far as I can tell from observing other painters at cons, I paint with a fairly thin consistency of paint for base coats, layering and glazes. The way I do steel/silver type NMM in particular uses really thin glazes, and I glaze skin a lot too. I haven\'t really ever noticed any problems thinning RMS paints other than a few colours separating sometimes (though far less than the kind of separation I got with some other paints I\'ve I tried). If anything, I\'d say they thin better for me than most other paints I\'ve tried.
That\'s not to say I haven\'t ever had any problems. I have had chalky problems with a handful of colours. The orange browns, which I think you mentioned elsewhere, and a couple of the olives. I can paint a base coat on one of those, then come back the next day and layers will go on chalky. Even just another thinned layer of the base coat colour will go chalky. Also I just can\'t get the earth and muddy browns to work for me. The paints behave fine, just can\'t seem to use the colours in a way that doesn\'t make me go blech.
I\'ve been gradually using a few more P3 paints. They do have a different feel to them for me, kind of like they\'re \'wetter\' than other paints I\'ve tried. So they\'re different to control. I\'ve painted two complete minis with them, but I still need to get enough practice with them enough to learn their ways. Still haven\'t quite got the hang of what consistency to use for smooth layers. What\'s worked nicely for me until I do figure that out is to use a P3 for a base and mix in an RMS colour for building up shading or highlight layers. (I do find the pots messy and wasteful of paint.)
Paint can be a pretty personal thing, and I know my tastes for what I find comfortable to work with have changed throughout the years I\'ve been painting. I hope you find what works for you.