I don't think we yet know for sure what route the tram-trains will take into the Piccadilly undercroft, but I accept hatter's point that if the tram-trains leave the current rail track shortly after Ashburys, and then head north-west to join the existing Metrolink line on Ashton Old Road, then that may possibly add a few minutes to the existing journey time, although we should remember that the current 25-minute journey time includes a few minutes waiting at a red signal outside Piccadilly! And if the new route does take a few minutes longer, that should be offset by the time saved through faster acceleration between Rose Hill and Ashburys. So overall, swings and roundabouts, it seems likely that it will still end up being 25-minute journey from Rose Hill to Piccadilly.
I also accept his point about the slow speed of street running in the city centre - for obvious safety reasons, it's the same everywhere when trams, vehicles and pedestrians share city streets.
However, I think hatter is missing a trick here:
I will have the added inconvenience of having to walk up escalators to access my mainline connection further adding to my journey
Not necessarily. Hatter will also have the option of getting off the tram-train at Romiley and having a same-platform change to a conventional train, which will get him via Hyde to the main Piccadilly station in 25 minutes.
Also here:
Marple passengers will see their 24 minute journey replaced by all stations via Hyde.
Here again, not necessarily. As a frequent user of Marple station (I never use Rose Hill because it's at the wrong end of Marple for me), I will have the option of getting a train to Romiley (we can assume there will still be one every 30 minutes), and changing there on the same platform to a tram-train which will take me through to the city centre. Or if I am planning to change trains at Piccadilly and go on by train to London or Leeds or wherever, I can stay on the train and go straight into the main Piccadilly platforms.
I accept that the tram-train is not a perfect solution, and has its drawbacks, but the advantages are clear:
1. A tram-train every 12 minutes, significantly increasing capacity.
2. Similar journey times into Piccadilly to those we have at present.
3. Direct services into and through the city centre, with same-platform connections to other parts of Greater Manchester.
4. Modern, quieter, more efficient and less polluting vehicles
5. A reduction in traffic congestion as increased capacity and a better service will attract more people off the roads and on to Metrolink.
And it's important to be realistic, and accept that things like this:
If it went underground in the city centre, I would be more supportive, it would become like the tube or Merseyrail system with 6 or 8 carriage trains able to run every minute or so.
...... just ain't gonna happen!