I think the Chipmunk has a number of advantages:
(a) Low wings
(b) Better handliing
(c) Fuel in the wings
(d) Good in Aerobatics
(e) Can be upgraded to the Supermunk with a Lycoming
(f) Thesedays mostly have a starter motor as opposed to starter cartrige
(g) It is a more modern aircraft and in service with the RAF/RN/Army until the late eighties and nineties