Vintage DD turntables. Are we living dangerously?

@lewm i rarely seen BA mats, when i tried to buy from BA direct it was sold out and you know it was many years ago. I hope that teamed up with Sakura they made something better, because it is not just a re-issue of BA-2 or BA-1. Compared to SAEC those mats must be fixed to the platter with tape (i'm thinking to do so), they are so light and the hole diameter is slightly bigger than needed.   

Yes, I think the BA website is kaput, last time I looked.  They were either bought or went out of business, for some reason.  One person suggested they had a lot of trouble manufacturing that mat, maybe because it may tend to be brittle and to fracture during the manufacture process.
Raul, The reason I and perhaps others settle for preferring one item vs another based on personal taste ("I like it", in other words) is because very rarely in this hobby can one draw a proven cause-effect relationship between the physical nature of the thing and the way the thing sounds.  For example, you correctly note that metals resonate. (You say at audio frequencies, but I would like to see proof even of that statement. I think the resonant frequency would also depend upon mass and shape, as well as on the material.)  You go on to claim that the resonant behavior at audio frequencies of a turntable mat feeds back into the stylus, which we can all agree would be undesirable.  What is your proof of that? Can you cite any scientifically done studies on resonance of turntable mats to support your claim?  Also, what would excite resonance in a metal mat?  Only energy that is delivered by a resonating LP.  But as you would also point out, energy transfer between a vinyl LP and a metal mat would be poor based on known physical laws; most resonant energy should be reflected back into the vinyl.  So, if a metal mat doesn't sound good to your ears, I would prefer to blame the poor capacity of a metal mat to absorb and dissipate energy in the LP that results from the vibration of the stylus tip.  That, at least, makes sense in theory that we know, but we have no data to prove that the phenomenon occurs to a significant degree.  So, instead of thinking I know why this or that happens in audio, I prefer to say here that I just like one thing or another, and it's only my opinion.  We're all different, and I choose not to impose my opinion on anyone else, except to make it plain what my opinion is.  If you want to take up the mantle of a guru with the final say on all audio issues, have fun.  Others are always going to have opinions that differ from yours.  Live with it.

A tiny hole in the mat near the spindle hole made to fix the lightweight SAEC MAT to the turntable spindle/platter, not to fix the MAT to the RECORD @bimasta 

But you have no idea how it works because you never seen SAEC manual and those parts are missing. Those holes are connected by very thin and flat metal bridge screwed to the mat, and it's under the record. 

RAUL disagrees with you, Chak —

"That tiny hole at the inner position in the SS300 is not to fix it to the spindle. SAEC makes a research about and they found out that the LP/records tend to slide through a metal mat surface so its advice is that with a small nail use that hole to fix the LP to the mat and for this you have to make a tiny hole on each LP at exactly the metal mat hole position then and before play you insert the tiny nail in the LP through the metal mat hole. In this way the mat and LP spins at unison/evenly."

Neither seems worth the bother to me, or even the few seconds to think about it. And note it could be done with any other mat regardless of the material, and no one ever bothered.