Well, cant understand that you were not happy with GigaSampler, GigaSampler should be the only program who can do that in a realistic style because of max. 4gb sample data! Well, maybe you should buy an other sample cd, i think, no synth could do that in the way you want, check out
www.bestservice.de, it's a germany company who owns a lot of sampling cd's around with online streaming demos, maybe you will find here what you need...?!
Frank