It is like the espresso version of tobacco. There is something to be said for small but strong portions.
I will try to update you when I manage to get some koiki. I will say a little about smoking Amsterdam Shag in the kiseru. For those who don't know it is a blend of virgina and kentucky usually used for rolling cigarettes. I have smoked this shag in my regular pipes and it is somewhat disappointing. In a regular pipe it tastes too airy and weak, with the virginia overpowering the kentucky. In the kiseru however the flavors are intensified, probably because of the small diameter of the bowl and the constricted stem. It tastes better in the kiseru than it does rolled in papers. It is surprisingly good.
I think I will probably try smoking some dark birds eye out of the kiseru. It is a stout blend in a regular pipe so it will be interesting to see how the flavor translates to the small kiseru.
Another type of pipe I have seen is, I suppose, a traditional Chinese pipe. It resembles a kiseru with the exception that the the mouthpiece is not made of metal. Instead it is some other material, I think maybe jade. Unlike the Japanese, the Chinese appear to clench their pipes. In many pictures they are smoking what appear to be either cigarettes or cigars out of their pipes. I don't know anything else about these Chinese pipes but I would be interested to learn more.