I bought a RSK mini from Aeromedix and so far it is great. I don't have any experience with field-sharpening a knife. My understanding is that S30V is a very hard steel. I would like to get a sharpening device that will:

1) work well on S30V
2) be as light & compact as possible; I want to be able to carry it as opposed to only using it on a workbench
3) is reasonably simple to learn to use properly

What's been working well for you guys?

It depends on your skill in sharpening a blade. I, again (as everyone already knows probably) advocate the inexpensive Smith's Diamond-coated pocket-sized hone steel. $5.98 at Wal-mart. You might also want to have something for touch-ups in the field - I sometimes put a pocket size Arkansas fine (white) stone or a Shrade honesteel in my bag too.

Otherwise, get the Lansky Quick Fix 2 Step Knife Sharpener. I just don't like using tungsten carbide to sharpen my knife. I found the similar Smith's carbide sharpeners to be damaging to the blade by not giving the correct angle I wanted. Those type sharpeners just take too much metal off at a time for my comfort, especially when I'm sharpening S30V, which ain't cheap.

If you don't have sharpening skills (like eyeballing the right angle), you might take some old knives you don't care anything about and practice sharpening or putting edges on knives. I sharpen knives alot and keep in practice now and then by sharpening friend's and family's kitchen and pocket knives for free while I watch the tube at night or visit them, etc.

I use a divice that bought in Wall Mart for less than $3. It is a yellow piece of plastic with a Carbide V and on the other side a Ceramic rods V. It is very simple, and portable. It works well for me.

That's the Smith's Carbide knife sharpener I was speaking of that is similar to the Lansky's. If it works for you, fine. I just hate it.

I second the small diamond coats and small Arkansa stones.

Also, practice touching up on smooth river rocks. IIRC S30V will retain its edge better if polished. D-2 does well with a toothy edge, S30V does not.

Here is what I am buying for everyone (6) in my family:
It is the 2-sided diamond plate ($14) and the Viking Whetstone from Ragweed Forge. The diamond plate works great on 154CM so it should work on S30V. The Viking Whetstone is something that looked pretty, but useless. I had been looking at them for a long time and finally had an order to justify getting one ($10). They work great for getting that smoothed and polished edge on your knife. I was really surprised how well it works. I am going to get everyone in the family one. They are about 3" long.