My sister is a violin and viola maker/restorer in Devon. She's currently got my viola and keeps it played. It took her some time to get used to it, after discovering that her viola (which she'd played throughout college) wasn't as good as she thought.
I've not read the study, and can't possibly comment on its quality or scientific validity, but I found personally that certain instruments are suited to you, and others aren't. The same is demonstrably true of guitars, though in theory there is far less variation, at least in style and wood choice (they're all maple as far as I'm aware...) within the violin/viola/cello world.
I presume all of the instruments were played in - that makes a massive difference to a violin. Certainly my viola sounded thin and scratchy after it hadn't been played for a few months. Once I'd played it back in over a period of a month or two, it was back to its warm, rich sound.
The last point I'd want to make is that just because an instrument is made by a 'big name', or because it has a ridiculous price (we've all seen some of those absurdly priced special editions, or Dumbles/Trainwrecks etc...), doesn't make it better than another (although it might be).
Roo