If we had unlimited paths and the approach to Nottingham station was easier, I would agree that city centre stations for Derby and Nottingham would be the optimum solution, in addition to the Toton Parkway station.
But we are path limited (as I pointed out in the other thread) and the approach to Nottingham is completely impractical.
Do we throw away a path giving Derby a service using a 200m compatible unit or do we use it for something else?
Do we route the line through Derby and completely ignore nottingham? Since that is the alternative as there will be no paths free to give Nottingham a train on a spur that goes nowhere afterwards?
Frankly, it depends on whether you want people on HS2 or not, and how well EMT or its successor competes with HS2. HS2's fastest time to Toton is 51 minutes. Allowing a 10-minutes connection and a 5-minute run to Nottingham Midland gives a time of 66 minutes for London Euston-Nottingham Midland. That's assuming they rely on a heavy-rail shuttle, trams would take significantly longer (although exactly how long is not stated).
So, 66 minutes to beat. EMT's current fastest time is the
Robin Hood, the 07:50 ex-Nottingham that arrives in St Pancras in 99 minutes. I assume that electrification is going to get it down to 90 minutes by better acceleration and 125 mph top speed. Tilt might reduce it to 80, but that's not going to happen. So, people can save 24 minutes by HS2, but that depends on one change and a heavy-rail shuttle.
This of course assumes you are starting at Nottingham Midland, for the western half of the city, taking the tram to Toton might be quicker, but not so for the eastern half. It also depends on the connection time working, and remember that Toton is a bit out of the way for a heavy-rail shuttle. How this is handled is up to whoever has the EMT franchise at the time, they might even refuse to serve Toton to avoid giving their rivals an advantage, or deliberately screw up the connections (I wouldn't recommend either, it wastes what might be a lucrative connection and most likely the DfT would clamp down on such practices).
It's possible that Toton will turn out to be another Ebbsfleet, where most trains zoom past and connections to the classic network are virtually impossible, depending on how they handle it. On the other hand, it could easily be a key interchange, but that depends on heavy-rail connections from the station. Having HS2 serve East Midlands Parkway (where the
Robin Hood stops) would have avoided any such risk and make access to Nottingham easier, but that's another issue. What this means for the possible Nottingham service is that it might be worthwhile to have 1tph replacing the current EMT Nottingham express, with the semi-fast retained.
Hopefully, HS2's planners will keep their options open. But if they're not to end up with stations in splendid isolation with nobody using them, they will have to remember that there is already a rail network out there, just waiting to bring passengers to them, or to be run onto.
Incidentally, my original ideas for HS2 involved running right through Nottingham and reopening Victoria, with trains from Grantham diverted into it. But then, they also ran via Rugby instead of Birningham.