The GT1000 is or was the "little brother" of the GT2000. The GT750 is the new baby in the family, with no teeth. Every opinion I have ever read is to the effect that the GT2000 stood alone in the Yamaha line-up. Even the GT1000 and certainly the GT750 were made to a much lower price point; they may look similar, but there are big differences from the GT2000. I have also seen all these variants, side by side in one case, during my several visits to Tokyo. In the flesh, the differences in quality of construction are obvious. I admit, however, that I have not heard the lesser models. Last spring I passed up a really mint, like new, GT2000L, which was for sale at ~$1800. I was sorely tempted, but sanity eventually ruled, since I have 5 TT's as it is. Anyway, it was a beautiful piece just to look at. Not a scratch on it. Probably would have cost $500 to $600 to ship to me on the East coast USA.
Removable headshell is a "feature" of a tonearm, not necessarily of a turntable. With some ingenuity, one can usually replace the factory supplied tonearms on these units. Back in those days, every tonearm on the market had a removable headshell. It was not until the advent of the Triplanar and probably a few others I can't think of that we had the choice of a fixed headshell, and as you know, some think that's a major improvement (in rigidity), not a negative.
Removable headshell is a "feature" of a tonearm, not necessarily of a turntable. With some ingenuity, one can usually replace the factory supplied tonearms on these units. Back in those days, every tonearm on the market had a removable headshell. It was not until the advent of the Triplanar and probably a few others I can't think of that we had the choice of a fixed headshell, and as you know, some think that's a major improvement (in rigidity), not a negative.