no problem glad to be of help.
The review was very favourable but I think Hi-Fi Choice magazine generally found some fault with every turntable back then except perhaps the Linn Sondek which was/is of course perfect
Pioneer were one of the best turntable makers in Japan in the 1970s and the lack of suspension thing is just a different design concept rather than a flaw. It's just that most houses in the UK have suspended wooden floors so the testing environment didn't favour decks which aimed at high mass for isolation. They did test them on wall shelves as well though and (guess what) there was always a great improvement. The X was probably just a European addition as you say.
The trend in tonearm's (in Europe anyway) back then was towards lower mass designs which require a more springy cartidge suspension and away from high mass and moving coils. The pendulum swung back in the '80s when companies like Rega and SME began to design with rigidity as the main paradigm and tonearms have been mostly medium mass ever since.
There is nothing wrong with high mass designs per se it just means that you need to match it with a lower compliance cart to keep the resonances out of the audible band.
You can also reduce the mass of the arm by swapping the 10.5gm Pioneer one for a lower mass headshell like the ADC magnesium ones. If you can get the arm mass down to 13gms or so it will be compatible with pretty much most carts on the market these days.
MC carts have always been more expensive as they are harder to make and they generally need higher quality phono stages requiring more gain.Lots of vintage amps have these facilities but new phonostages which are designed for moving coil tend to be expensive these days.
There are exceptions like the Denon DL110
http://www.amazon.com/Denon-DL110-Ou.../dp/B000I1YLG0 which has a higher output and can run on a regular MM phonostage.The ADC MM cart I mentioned is very good though and there are bound to be others around.
As far as mats go everyone including Linn used rubber back then apart from vestigal type designs like Transcriptors and Bang and Olufsen so magazines generally just criticised the weight of the rubber!
Mats are important to reduce ringing in metal platters and adavnces have been made by using materials like acrylic and more complex plastics which work better than rubber and needn't be expensive. Look on ebay. By all means make a cork one. I've never tried one personally but it will certainly influence the sound whether it's better than rubber is pretty subjective.