Yup - this seems to be what kills 90% of VQ's from my experience.
I also would recommended used/low mileage engine over a re-build. But that said, I sell engines, so I am biased I guess.
Do they offer a multi-year guarantee? A lot of re-builders offer a 2-4 year limted mileage when my friend's have had it done? E.g. one of the well known Mazda re-furbers offers 4 years infinite miles guarantee, for a £4k re-build.
ta