Hey Emanuel,
I saw your thread and decided to reply, though I am definitely not an expert in any way on the Symphonic Cube, but from what I've read, heard on VSL, and learned a bit myself I would not be so quick to decide to resell the VI Solo Strings library. As far as reselling is concerned I think one of the VSL folks needs to answer that part of your question, but if you are just now purchasing the Cube I would deeply consider holding on to Solo Strings. Not only is it a great library (check out this solo strings mock-up by Jay Bacal: http://community.vsl.co.at/forums/t/17673.aspx), but I think a lot of people use it with orchestral strings to help with the overall mix, even if they are not using it for solo parts. See here as just one example: http://community.vsl.co.at/forums/t/17524.aspx?PageIndex=2 Using a sample library for an orchestral mock-up is not like writing for a real orchestra (as I'm starting to learn through experience) and that sometimes in order to get a more realistic sound, you have to use unconventional means or tricks that wouldn't be necessary with a real orchestra which might include using solo strings when there are no written solo string parts. There that's all I'm going to say about that. VSL products are amazing, I'm sure you'll be very happy with them.
Brian