This would be a minor change but I think its an important one. I think all samples after slicing should default to cut mode. I don't see the use of them defaulting to once, because they will overlap each other.
IIRC in case you weren't already aware you can adjust the sample playback mode for all kit samples at once by using the affect all toggle while changing the playback mode.
I'd agree that cut would be a better default. Once is basically a less flexible cut, with the only advantage being that you don't have to see a held note on the grid.
afaik in slice mode samples are also set to cut or once based on the sample length (something like >2s => cut, <2s => once). as usual. yeah the affect all batch command is killer, use it a lot.
i actually almost never use once mode, cut is more flexible. i fully agree with "Once is basically a less flexible cut"
i dont want a sample set to once (by default), regardless if i am in slicer or normal kit mode.
we could add that to http://forums.synthstrom.com/discussion/283/global-defaults-menu#latest (oldie but goldie by rpc)