My recommendation is to use the computer for sampling unless you're going to just sample a few things here and there. If you must use a workstation to create multi sample instruments where the samples need processing ...forget it, you're much better off in a computer. None of the workstations are friendly to developing multi-sampled instruments of say 10 samples or more. If those samples need editing and you'd like to maintain your sanity... don't even dream of using a workstation.
Now, if you must use a workstation, the only one to use would be the Roland because of its editor which you can use in the computer. It's a limited function editor however, and doesn't include any processing functions. It's looping capability (as of Version 2.0) is very primitive and will take you at least 5 to 10 times longer to do your looping than a decent piece of computer software. If you don't plan on editing or processing your samples ...for quick mapping and parameter tweeks the Roland is way beyond the stumbling around the clumsy and non-intuitive interfaces of Motif and Korg.
Another snag is the problem with the Roland audio file header. Basically, (and there might be a work around although Roland personel don't know of one) if you take a wave file from your computer and stuff it into the Fantom, the Roland conversion strips out the loop information. Someone else here may have some info on that. I had to put up with it because I didn't have time to fiddle around... that's why I can tell you the looping function in the editor is very basic.
William
williamcoakley.com