Hi Halco,
I was also blown away the first time I auditioned the Sirius III at the dealer over 10 years ago! However, I didn't notice any lack of mid-bass to lower-bass definition and power, maybe due to the different setup. Not sure about the air-supply in the Sirius III, but the stock air-supply for my Rockport 6000 arm is certainly inadequate, and major improvement can be had with a Jun Air compressor with integral surge tanks and multilevel of air regulations. With this upgrade, I don't feel the tangential arm is lacking in bass definition and power. If pressed, I may admit that the bass quantity maybe so very slightly less than arms like the FR64S, but the soundstage depth and width is something to die for.
But then, I must agree the performance of these flagship vintage DD turntables are shocking. It would be interesting if a direct comparison with the Sirius III could be arranged!
I have just managed to get hold of a Technics SP10MK3 from Japan, so will have some fun setting it up in coming weeks!
Cheers