Thanks guys for the advice and interesting observations - there appear to be a lot of Tak supporters out there, not to mention afficionados of large-aperture reflectors.
I am sticking with either option 1 or 2; the F7.9 APM-LZOS 152mm triple apo may well be the scope I buy - expensive but well made with premium Russian glass and a great focuser.
Cheers,
Richard