I listened to the Ballad strings again, I can't believe these convince you, as you like Kurzweil strings so much. What a difference. The Motif Romance Strings are not very realistic either, but to me the sample at least sounds more dense and not so airy.
Generally, for professional strings in hardware instruments, I would always look for additional libraries/ expansions, AFAIK these are the only ones that have separate section samples for violins, viola and celli each.