excrewingbod:
In some parts of the UK (Up here in Scotland where there are fewer airfields and plenty of obstructions to line-of-sight), D&D does have its limitations at low/GA altitudes.
The main reason I was given for making calls on the current frequency is that you are already talking to someone, hopefully they have you on radar and can advise you better and certainly the last thing you want to od is change something you don't need to and end up not being able to talk to anyone :-)
If you can't raise anyone or if you are talking to a "roger, out" FIS, you may be better off switching to 121.5 if you are temporarily uncertain of your position :-)