I love dark grey but it may feel a bit closed in. Perhaps dark grey lowers and a lighter grey for uppers.
If you love it, do it. I personally am not a fan of gray except for accents as to me it is institutional, cold and unwelcoming. But this is about you, not me. If you use gray, brighten up other areas and use color so that it doesn't end up looking like a dark cave - unless that's the look you are going for. It is your space, and regardless of what others think, you should do what makes you happy.
It is a lot of work to paint any cabinets. What are the cabinets made out of, and finished with? The outcome of this project partially depends on the type of wood that the cabinets were originally built with, and their quality.
It is very important to follow all the recommended steps, with no short cuts, and use quality tools and materials. Even so, the results do not always meet with expectations.
I live in an RV...the lighter the paint, the better, unless you want to use a lot of electric lights. The dark colors tend to make enclosed spaces look like caves and will cost a bundle to light up once the sun goes down. If you use lighter colors, you will save some money. Good luck!