Have you listened to an RP 8 in controlled circumstances, and if so, how did it fall short? That would seem to be of help to the OP.Likewise!
From your post I can only assume that the Linn LP12 is not a well regarded vintage machine, as “...all the well-regarded vintage machines.......have powerful drive motors.” I tend to differ on that point finding the Linn to be a well regarded vintage machine with a different design brief.
Since it was designed as a specialist product, rather than for cueing in radio stations, a less powerful motor was used as it produces less vibration than a high torque motor. What vibration is left is mitigated by the belt rather than being directly transmitted to the platter by an idler or direct drive. The trade off is less secure speed accuracy and the benefit is a lower noise floor. Those are intentional design briefs. And though you may find the resulting sound to be inferior, it seems very hard to think that saying that the Linn is not well regarded can only be the result of turning a blind eye to the historical significance and longevity of the product.
For a second I thought that you might not consider it vintage due to the age. But the SP10 came out in ‘70 and the Linn in ‘72.
Happy holidays and all the best,
Its been a while since hearing the Rega in a customer's home. So I can't say that I've compared them. But I have compared the Technics to other tables such as the Kuzma, which is considerably more upscale than the Rega- if it were between the Kuzma and the Rega, I'd take the Kuzma in a heartbeat. The thing is, the Technics is able to keep up with the Kuzma (which is an excellent machine). The simple fact is, Technics did their homework and so it gives turntables costing a lot more a run for the money. IMO, most high end audio turntable manufacturers should be really worried about Technics right now.