I just made some measurements because I'm curious...in case this is of any help here is what I got.
I used Synchronized Dim Brass Trumpets XF
The default from factory is CC7=90, CC1=127, CC11=127. Max peak = -7.32 dBFS, RMS=20.84 dBFS
Moving CC7 to full max, I get Max Peak = -1.29 dBFS, RMS=-15.10 dBFS
So the first observation is that when all controls are turned all the way up, Synchronized Dim Brass Trumpet ALL XF gets very very close to clipping. Dangerously close actually, but it only clipped for me if and when I played a chord, which its not designed to be used that way anyway. So the point is, it looks to me that VSL endeavored to keep the signal coming out of Synchron in this instrument as close to 0 dBFS as they felt was possible.
It also shows that their default setting for cc7=90, which lowers peak to -7.32 dBFS, which presumably is how much they feel Trumpets need to be lower to balance realistically with other Synchron instruments.
Trumpet is a fairly loud instrument in the orch anyway, and at -7 dBFS its not at all a problematic level in terms of headroom IMHO.
Change CC11=110 and we get Max Peak = -9.90 dBFS, RMS=-23.34 dBFS
Now in my view that is still totally usable, but its also a little bit low, because of the CC11 home base point set at 87% of full unity.
In order to use a trim plugin to bring all the instruments back up together...I believe a corresponding gain plugin bump would be: +2.5db, which resulted in following measurements: Max Peak= -7.36 dBFS, RMS=-20.85 dBFS
That is close enough for government work, as we say....
I do want to point out one more thing though, if you bump the level back up using either a trim plugin or CC7, then later end up taking CC11 to "Eleven" (CC11=127), then you hit MaxPeak = -4.9 dBFS and RMS=-18.3 dBFS.
That's still not clipping range, so may be ok...but if working with something like percussion or something that has capability to get really loud, there is always a remote possibility of clipping that instrument if and when you push it to "Eleven" with the CC's and the Trim plugin adding +2.5db on top of that. So watch out for that. For example, with this instrument, if I move both CC7 and CC11 to max (while sending through the trim plugin at +2.5db), it definitely clipped.
One advantage of using CC7 to compensate, rather than a trim plugin is that you wouldn't have to worry about clipping like that (as long as you don't play chords in this case). Because VSL gain staged this instrument to peak out at -1.29db when all CC's are at full max and playing monophonic lines.
The disadvantage of compensating with CC7 is that some instruments may not have enough room at the top to fully compensate them, depending on what VSL's default CC7 setting was. Also, you have to make this adjustment in every single instrument preset as custom presets (which you're doing anyway when you set CC11 to 110).. whereas with the trim plugin you can send them all through a bus and compensate them all with a single trim plugin.
Hope that makes sense.