Probably the same kind of guy that would sell a PSR3K and get a Ketron... In other words, anyone who is looking for a better sound and functionality..!

Yes, of course, if you are not doing studio production, or need this for remote operation, rather than at home, it's not practical, but PLENTY of home amateurs AND pros use GIGA sampler and other soft-synths at home, to get a higher level of quality sound than they can get out of most hardware keyboards...