Completely biased response:
Any "well working", stock Stellavox will sound better than a stock Lyrec or Nagra. Plus, their electronics can be "tweaked" to significantly widen the gap. Yes, changing the spring belt to neoprene on the SP7 (only neoprene on the 8 and 9) does quiet the machine down; and worn bearings make noise.
A TD-9 with the proper headblock and tensiometers could handle 1/4", 1/2", 16mm, 17.5mm and 35mm tapes. Good luck in finding them - have a firstborne to swap? And, their repro/record electronics are basically the same as the SP series. Reliability is questionable - there are at least two broken ones (out of maybe 15) in the US.
Charles