Hey Folks,
Although I've never actually come across this problem (even though I'm a *huge* fan of the solo strings VIs, and get a lot of use out of them) it seems to me you should be using a regular "long notes" articulation, rather than the legato instruments for these long notes that are giving you trouble. As you'd discover searching around the forum a little more, the legato instruments really aren't designed for playing long notes, their primary role is to provide the sampled legato transition. I think the "separated" notes from the legato patches are taken from the repetition articulations/samples, so they probably aren't as long as the sustained long notes, but I'm not certain. So if you've got separate long notes, I'd try a perf-rep_legato, and if that doesn't work, try the "sus" long notes (the progressive vib one is *hot*, IMO).
The lack of "consistency" in notes is probably due to the alternations pre-programmed into the VIs for "separated" notes on the legato instruments. I've never noticed them being different lengths, mind you, but I'd imagine that's what you're hearing.
I know this could be irritating if you're an experienced orchestrator, so skip this if you are...
But on a general orchestration note, keep in mind that if your dynamic is forte, or better, you probably will never get a 5 second note at all (without rebowing)... the bow's not long enough! [;)] Single, soft notes can be held much longer than loud notes. So, unless the sample has the rebow included, which some do (*very* cool, IMO), then your forte notes won't sustain as long, under a single bow, as your piano notes. I tend to compose in a way that's very bowing conscious, so I just don't come up against note duration problems (which is probably why I haven't noticed yet, in several months of solo string VI use). But one trick for getting around this note-length issue, provided it is related to dynamics, might be to use separate controllers for selecting the dynamic of the sample (normally assigned to noteon velocity) and the actual volume. This way, you could be playing the p, or mp sample, but at an ff volume. This isn't a great option, IMO, because you'll get the wrong colour out of the instrument, but it seems to me I've heard of people doing this. Personally, I'd track down that sustain articulation with the rebows recorded... wish I could remember which it is... You'll know when you find it though, because you'll actually hear the rebows appearing as you go up in dynamic. Yum. Reality: you gotta love it!
Anyway, just some thoughts. Hope this helps.
J.