Meh! Yo can use Kontact .. but you'd be eating up valuble Ram and CPU cycles to run the program outside of Logic. The beauty of running EXS is that it's fully integrated into Logic, ... and if I read the forum posts right .. can actually use more of the systems memory than GIGA can at present.
But yes your only real choice is Logic. I'm a cubase user myself, so it wasn't easy for me to accept the change. I even wrote recently to Apple request some cubase style features for logic ... who knows! ... but my point is is that I have adpated to Logic well and find it now very easy to work with.
You cann use Cubase and Kontact on the mac quite effectively ... but Logic offers the premium amount of VSL performance.
Hetoreyn