What is wrong with saying hello and thankyou to someone in centre or in a tower?
Surely that is just common courtesy?
AaaaaahhhH!!!, the good old days?? I got my very first 225 ( and if you don't know what that is, ask any gray haired pilot) for saying "goodnight and thanks" at ASBK (now YSBK) ---- not standard phraseology, you know.
Seriously, cut the cackle when the frequency is busy (which is now never at YSBK), but if it's quiet, what's the harm.
Tootle pip!!
PS: What with "professional", there is no differentiation between communications procedures for "professionals" and others, and some of the worst examples of poor communications are from working commercial pilots, who undoubtedly style themselves as "professional" because they have a CPL or higher license.