Here is the last installment in the XM-18 testing vs. a Delica. I dropped the Griptillian, as I was never able to get a satisfactory edge on it.
I did some edge holding tests cutting cardboard and found that in the Delica vs. XM-18 contest, the Delica won every time, but only by a slight margin. In 3 out of 3 tests, cutting cardboard and push cutting string to test sharpness, the Delica came out with a slight lead each time. The Delica was consistently sharper than the XM-18 using the same sharpening procedure, 220 Norton water stone, followed by Sharpmaker medium triangles, in the Sharpmaker for the Delica (20 degrees/side) and held freehand for the XM-18 (23 dps). The Delica's advantage may lie mostly in this little head start, though as cutting continued, the margin seemed to increase.
I also did some chopping and batoning with each knife. I chopped or batoned through some bamboo skewers with each knife. The batoning was done with a piece of wood. Surprisingly, the Delica was behind the XM-18 on this test. The edge reflected light after just a few hits on the Delica, while the XM-18 emerged unscatheds. The chopping tests revealed some handle issues with the XM-18. Every hot spot on the handle, from the spine jimping to the clip, could be felt when cutting through the bamboo. Again here the XM-18 has an advantage, as the Delica's edge took damage before the XM-18. I suspect the slight difference in edge angle had something to do with the differences are the cause, but more testing is in order, and I have to send it along.
Overall impressions of the XM are that it's a very nice knife. All the surfaces are finished appropriate to their use, ie lock bar and tang faces, etc. The opening is very smooth. The detent is right on. It carries easily, and is not intrusive. I really like the blade profile/silhouette. The shape is handy for many things, with enough belly and tip for general use.
However, I had some issues with it in use. Given the blade play, clip wiggle, difficulty sharpening, and lack of a larger handle, I have to say I'd stick with the Delica before I'd buy an xm-18.