Claude that's a nice demo. Though I thought you might have used the performance trills on the last one, it shows how much more complex the Dimension sound is. The Chamber cellos sound like great but uniform ensemble samples but the Dimension have that individual player quality impossible with ensemble sampling.
The purpose of Dimension is not to replace the older libraries for single line performance, but to allow free use of divisi and unison, as well as enriching the overall string timbres of the various VSL libraries. However, they can be used as shown here and other recordings as the only string sounds in a smaller ensemble. Also, it is possible to double the sound with transpose/pitch shift for larger and even more complex sounds.
The use of individual players vs. an entire ensemble of Dimension is an interesting question. I have a tendency to want each player totally separate on his own MIDI channel. However, I have noticed how with the great new humanize and tuning preset functions in VI you can load all individual players in MIR (or other reverb though MIR is better for these orchestral sounds) and give them the same channel for a single line and they truly behave exactly like individual players. i have been experimenting extensively with humanize in both the MIDI and the corresponding VI instruments and trying to push them as far as I can into the complexities of tuning and timing one hears in live ensembles. This is why i am so enthusiastic about the Dimension instruments because they have that exponential increase in complexity. Though the other VSL string libraries are still as essential because they provide a starting point that you can add to with Dimension.
I did that on my Vertigo demo - http://www.vsl.co.at/Player2.aspx?Lang=1&DemoID=5980 which combined the Dimension violins in 6 part divisi, with a "concertmaster" Solo violin and then in the big tutti at the end the Appassionata.