The DMTs mini sharps are reasonably good, but I do seem to have trouble sharpening ZDP-189 steel (HRC of 65), which is very difficult to sharpen. I seem to get better results with a cheap diamond rod sharpener (powerfix) I picked up from a local discount store for about $4. It looks to be identical to the Gerber Sharpener available here;

http://www.amazon.co.uk/Gerber-09841-Diamond-Knife-Sharpener/dp/B0001WOTHC

Using the Powerfix Pen diamond rod and a Red DMT F70F, covers most needs.

It's most likely because the rod sharpener is a courser grit stone than the DMT you were using. When sharpening harder steels it really becomes necessary to start with a course grit and work your way down (depending on how fine you want the edge). If you try to sharpen a ZDP or S30V blade with just a Fine stone, you'll be there all day.

This is why I like the Diafold models. I find the Blue (Course) side can put a reasonably quick edge on most blades, then I can clean it up with the Red (Fine) side if I want a more polished edge. With ZDP I would even think about maybe going with the Black (extra course)/Blue model just to save time.

Back in November of last year I found a small smith's brand
pull through knife sharpener. yha these sometimes stink
but I picked it up real cheap and tested it so far I like it
it wont work with a knife with a poor relief edge it has a
coarse and a fine sharpening edge. i think the fine edge is
crapy. and its real easy to work no skill needed.

purchased at our favorite China store WallMart

Litlefoot01
protect our freedoms.

I prefer synthetic waterstones for most of my sharpening, with DMT Dia-sharp diamond plates for coarse work, but for simple sharpening in the field it's tough to beat the Edgemaker Pro system. I agree that most pull-throughs are junk but the EMP is different. The compound steels flex inward under pressure, using leverage to help remove steel & put an edge on quickly. A set of all three grits is only $30 with free shipping, but if you want to economize the 2 pc kit (comprising the top 3 out of the 4 available grits) will suffice. In practice the yellow Honer is enough if you use it regularly. My dad gave me on that he'd been using for 15 years and it still works well.

Of course, all pull throughs have some limitations. The EMP has worked well on 95% of the blades I've tried it on but I suppose there are some it wouldn't like. It's not designed to do convex so it wouldn't be ideal for a Bark River or something like that. But it's effective on the vast majority of knives.

Sharpeners largely depend on the blade shape and edge type.
This is field work sharpening.
For "easy " shapes like a standard clip point, drop point, spear point or pukko, without serrations I tend to use the DMT DIAFOLD (2 sided diamond stone linked to by others), a Spyderco Double stuff pocket stone (the 2 grades of ceramic used in their Triangle sharpener, but flat simmilar to a 3/4"x4" stone).

This is done more at home. (one of the above stones is there to fix nicks and gouges in the edge while out in the field).
Some of my blades and all my axes/hawks have a convex edge so I use a piece of wet-dry sandpaper in varying grits on a strop board (wood bord with leather pad, mine has polishing compound addded to the leather)Or you can do the sandpaper over a mouse pad.

This is both Field and home techniques.
Then you get into inward curving or undulating cutting edges (kukri, karambit, etc) these tend to take a round (diamond rod, round or 1/2 round file, or round ceramic rod), triangular (various ceramic sticks) or convexed (the top of some old sanding blocks) sharpening surface.

The pull through style sharpeners are ok for basic edge shaping in my experience, unfortunately with some knives they tend to leave a bur on the edge and require a light touch on one of the above mentioned devices to finish the job. Case in point I sharpend a friend work knife yesterday that she has used a accusharp on for about 2 years, 5 minutes touching up the bur and getting it shaving sharp.

Other things play into what a specific blade needs to be sharpened. Harder steels seem to work with pull trough sharpeners better, softer steels seem more inclined to like being caressed with files, ceramic or natural stones, while the in between hardnesses like most of everything with an occasional touch up on one of the first three methods.

There are also various angle guide tools to maintain the sharpening angle. I have used a few, they help when learning to sharpen by hand for some people.

Over all, it seems to be a trade off of space and weight for the method(s) you choose to sharpen with. Axes and machetes can both be repaired with a file in the field but, is the extra weight of the file or files necessary? Are any of your other blades soft enough to not force the file to slip off it whitout removing metal?

I have carried the Spyderco double stuff stone for nearly 10 years and the DMT diafold fo almost 8. They work for me for my EDC blades. I have pull trough sharpeners or back up diamond rods in most of my bags or packs I use.

Just throwing some of my seldom useful information out there.