I painted a second set of "Skavens" but this time with the dipping technique. As you can see below, there is not much difference in result when compared to the ones I have painted before, but there is a huge difference in time:
The model on the left has been primed in white and then painted with basic colours and finally dipped in varnish stained, whereas the one on the left has been primed in black and then retouched it with a brush to cover those holes where the spray doesn't reach. After that, it's been drybrushed it in pale grey and then in white, and finally painted with contrast paints. I'd say that each figure on the right took me six more times to finish it than the one on the left!
I also have to say that I made some mistakes painting the latest set and that next time they will turn out better.
In a nutshell, varnish stain dipped figures are faster and cheaper to paint and a much harder finish, but none of this methods convince me. I'm sure it would be different if I used Mixwax but it is impossible to get it in Spain, sigh!