Halcro,
The rubber straps are flat bungee cords - available at home-goods or hardware stores. Yes I clearly hear an improvement with them - that tin can needs dampening. Perhaps it would be better to coat it somehow.
My observations on poorly recorded albums is that the better I make my playback system the better I can hear the flaws in the album. I am quicker to chuck bad records now than I was in the past because they are unlistenable. Of course the good albums just open up wonders.
As far as plinth/no plinth, Lew and I just exchanged posts on Vinyl Asylum and he easily stated that bad plinths cause problems but that good plinths can be a benefit. My opinion is that good plinths sound better than bad plinths but at least in the case of good DD tables no plinth is even better.
Lew also made the point (Lew my apologies for quoting you and especially if I, by some stupidity on my part, misquote you) that idler drive tables require a good plinth and that string/belt drives often don't. That may well be so, but it doesn't say anything good about the vibration issues of idler drives, does it.
As I have stated before, somewhere, a plinth is unnecessary and often undesirable because it collects, holds, and returns vibration to the tone-arm and turntable. I hear the loss of this vibration as gain in all things musical - like going to a better turntable. Things improved for me as I went from full plinth to semi-plinth to no plinth. I am not going back.