That is good question. I think that when it matters the masters tell us so I.e. when you are doing the krump against the master, you strike him with the short edge.
If you do the abzetsen with the krump (the one in Ringeck which that has two counters and that use the shrankhut as part of the deflection) you hit him with whatever you edge is handy.
It is really like should it be with crossed hands or not the crump is probably the strike where there is much variation between authors.
If I am not mistaken and taking to krump to the hand
Lew, Vdantzig, say with crossed hands and long edge
Except when it is from a left schankhurt when It is the short edge
Speyer says that but as well with extended arms and throwing the point.
(And I think that is what ringeck is saying too)
Goliath say like Vdantzig but the picture looks like this
http://schielhau.org/images/43.jpg other wise as long as you step on the side hit the hands with a somewhat curved strike, I would say we are smoking, personally I tend to use the long or short edge according to where and how far their hands are and where I want to go.
One Ringeck to bring them all In the Land of Windsor where phlip phlop live.