qwin, After your last one or two posts, I am no longer certain what is your position. The SP10 Mk3 is simply in another league from either the SL1200 Mk2 or the 1200G series, BUT, as Raul already mentioned, no Technics turntable used a coreless motor before they introduced the current G series and the SP10R. Your 1200 Mk2 has an iron core motor, as did all other Technics tables of the earlier era. If you want to make a comparison of old vs new Technics, you would compare the new SP10R (top of the line, coreless motor) to the SP10 Mk3 (top of the vintage line, most powerful iron core motor ever used in a commercial DD TT). When I say "powerful", I am referring to torque. The high torque of the Mk3 motor was needed to control its 21-lb platter. I have owned SP10 Mk2 (two samples) and I currently own and use a Mk3. The latter is a more neutral sounding turntable. I am sure the SP10R is competitive with the Mk3. All of these need a proper plinth (but "proper" is another debatable adjective). The way you talk about the SL1200 Mk2 vs the 1200G, it seems you own or have owned both. Is that the case? If so, which version of the G series? Thanks.
Coreless motors ought to be inherently superior for use in a DD turntable because of the lack of cogging, but their drawback is they need to be physically large to produce a lot of torque and they produce heat as they get more powerful. In the vintage era, Kenwood, Yamaha, and Pioneer, at least, marketed turntables with coreless motors. Probably there were others that escape my memory. The iron core SP10 Mk3 motor uses 12 iron core poles. The more poles, the smoother the ride, the lower the problem of cogging. That’s another way to approach the issue.