This matter isn't black and white. The legato scripts have several advantages that the "real" sampled legato doesn't have.@William said:
Suppose someone creates an incredibly good faked legato, with harmonics and formants and all the associated acoustical elements correctly offset and shifted, etc. Someone else will still come along, and incorporate a true legato later on. And then what good is the fake?
The synthesized "fake" legato doesn't need more memory. The VSL legato instruments take a terrible amount of memory and with 32 bit computers you can't load very many of them. In a basic orchestral setup I run out of memory very fast but I have plenty of processing power left. Using synthesized legato would take some of the free processing power and give me a lot of memory space to load more instruments and articulations.
The synthesized legato can be added to any sample library afterwards. I wouldn't mind having scripted legato for EWQL RA or scripted VSL legato supporting all available dynamic layers. Herb just said that they are trying to use the available legato samples in four layer VI patches but that will take a lot more memory and it won't help the users without the new VI versions.
The synthesized legato is cheaper to do as there isn't need to record, edit and program all those legato samples. That should mean that libraries with synthesized legato can be sold cheaper and still make more profit for the producer.
The VSL sampled legato works very well with woodwinds and brass but not so well with strings. Most likely I'll start using a script with my VSL strings as soon as there is one available. I don't assume that the VSL woodwinds would sound any better with a script, most likely it's the other way around.
Of course there are disadvantages as well. You'll need Kontakt 2 which might or might not be a problem. For me it's my preferred sampler because of VSL's sampled legato scripts and a couple of nice pianos. There also might be some licencing costs or other issues if the script isn't written by the producer. And certainly the scripted legato can sound fake.
Most likely there are more pros and cons but these were the first to come to my mind.