I think this is a fine varmint cartridge and I have come close to buying one myself. Reading the various notions about why the 243 outsells it, one of the points I have heard is that it does not fit into the medium length action that a 243 does.

It is in a length group with the old mausers so my "vote" is long. But not long like the Holland & Hollands. Of course, in a single shot action length is a moot point. Go single! :-)