It's a question of using the most appropriate tool for the task in hand...
I always thought that the Dalton work we did during Gnat groundschool was a bit daft - but it was certainly corrrect for pre-flight planning for Chipmunk navigation at 2500ft.
On the JP 125 hr course (before the days of Gp1 Ph 1 or whatever it was called), medium level and radio aids navigation exercises were pre-planned using a Dalton computer; however, MDR was also taught for other applications. The low level technique, taught later, was, of course, totally different.
Personally I think that the Dalton should be used at the elementary stage for pre-flight planning; MDR should be left until later stages of training and therafter the use of the Dalton should be 'as required' only.