I would naively have thought this special option (module) is not needed anymore at all, as the T tracks are treated like any other track type. Is this not true?
Yes, that was kind of the hope I had too, but after having a chat with @isanders it seems to be needed to be quite a special reco sequence. As in which one can be fitted, have Rich pids, etc. Some will need to persist unfitted (no pid) seed tracks, others will need special filtering and then fitting with subsequent Rich/calo/muon pid. Anyway, something for another MR (than the one for track splitting).