Regarding the Kronos, yes, I would consider its expansions as the closest (at least technically) to software libraries you can get on a synth, I just recommended someone to have a look at it - for me personally, it would mean to give up the lightweight MoXF and carry a 13.9 kilogram keyboard to each church wedding. That's why I'm so crazy about a module.
With respect to this specific demo and expansion, I'm not sure... the demo boasts so much with gigantic percussion sounds and octaved strings with a strong-vibrato solo violin on top of it, I'd rather want to hear how a plain Beethoven symphony would sound with it in order to be sure how realistic it really is.
In that respect, I like the Kurzweil examples Mikem posted even better - even if this is not up-to-date technology, and there are some details where you hear it: the very high string section tones do sound somewhat synthetic, the piano is sub-standard, and at one point I heard a not-so-perfect trumpet. Kurzweil have certainly also rested on their laurels too long... Actually I think the Roland SRX 04 and 10 largely live up to these Kurzweil sounds (SRX 10 probably exceeds them), Roland woodwinds might be a bit worse, but IMO it's more a question of how much detail you put into the sequencer tracks.