I go in to Manchester from Marple (as it's slightly quicker) but I come back at various times and just take whichever of the Marple/Rose Hill trains comes first. It has never been queried, even by the occasional ticket inspectors at the stations. They do all pass through Romiley, after all.
But, sadly, I have fallen asleep on the Marple train and ended up in New Mills. (Could have been worse: some of the trains go to Sheffield!). Too embarassed to ring my wife, so ended up with an hour's walk back along the canal.
The new trains are much more comfortable (and the WiFi is great!), but they are beginning to get crowded so it will be nice to have the remaining services reinstated.