Hi Crusoe,
To begin with: I could work well with Synchron Strings 1, also with the legato. It was just a little bit of work to overlap a little the notes. So I don't know if I am the right person to tell you about the legato of Synchron Strings Pro.
But okay: my 5 cents.
Yesterday I started working with "SSP" and Dorico. I'm just working on a piece for String orchestra. When I coupled the SSP to the music I had to adjust of course a lot, because it responds a little different from SS1. Today I went on working. Here a few of my experiences until this moment.
1. In SS1 I started always with some equing (how do you write that in English?). Here nothing. No extra reverb. I choose my microphones and off I went. (A very subjective experience of mine here: sometimes the sound is in a way just as breakable as in real life with a string orchestra, but you can build with it beautiful melodies, chords, accents, etc.)
2. The senza vibrato samples are great, because the sound is the same as the vibrato patches (without the vibrato of course), so you can very good xfade them, from senza vibrato, to regular or molto vibrato. In the past I discovered, that the senza vibrato patches were often a little brighter. I looks like that vibrato has an influence on the stroke. Of course. But it looks like now that the influence of vibrato is implemented in the non vibrato tones. Really, they are crafsmen and craftswomen.
3. In Dorico I had adjusted much tones of the piece with a little overlapping for a decent legato. Now I had to reduce or even delete most overlappings. And I have to say: I like this legato very much. I think (but I can't say of course), that you will enjoy this legato patches too.
4. Portamento. Until now I was not always a fan of Portamento, because it was often not totally the real thing (but sometimes it sounded nice in my ears). This portamento is very natural, of course the time stretch feature is a great help here. Unfortunately I encountered a bug with the violas, but that I report that to VSL. I'm sure they will fix that.
So I hope, this helps a little. I can't give you an audio example at this moment, because I have not finished yet my piece. But there are examples on the internet.
Kind regards.