not used either deck , can't say which is better ....can say that vintage might not
really play into your best situation.
with a few exceptions ,dual decks were a compromise in sound and performance .
teac and sony ,denon ... made a few Pro-Sumer oriented decks which were very
expensive at the time. if the yamaha anything is like these ,it's prob . better than
that technics dual deck , but technics and yamaha both sold entry level junk , too...,
neither would be considered "vintage classics" .
if you really want "vintage" that's superior to modern stuff... nakamichi ,tandberg ,
revox , luxman..... better 3-head pioneer , Teac , yamaha, sony , denon, h/k,...
even Technics made a few memorable 3-heads ........... all single decks.
for just needing 2 cassette wells for dubbing....why not get a couple'a NAK BX-1,2,3
150 or 300's ? they sell for little $$ now because ,while vintage ,they aren't "classics",
but will outperform any dual deck ever made...and most singles.
otherwise....i'd suggest buying something relatively new that won't break down or
require immediate attention . if you buy something old and mediocre you'll be gaining
very little other than repair headaches.