I have played with the VH45DE and fitted it into a 180sx, see thread.
http://www.skylinesaustralia.com/forums/topic/275110-180sx-vh45/page__p__4742872__hl__vh45de+180sx__fromsearch__1#entry4742872
Drove it briefly today after my mate had a drive as it's his car, all I can say is they are great, responsive and pretty big lol.
Weight wise, they only weigh 20kg more than say an SR20DET setup (engine, ancillaries, manifold, turbo, intercooler etc).
Being all alloy helps in the weight stakes, and the thing drives great, considering engine usually lugs a 1800kg plus car and is now pulling 1250kg or less, doesn't feel nose heavy.
VH45, meh, next I'd like to try a VK56DE+TT in a 34GTR!!!