This is very unusual but I agree with Google Translate this once on the translation but not in what you want to accomplish.
First let me say that I understand the "debe de ser" use as explained in @fedorqui's answer but in Colombia we many times omit "de" and just say "debe ser muy experimentado". This part is where I agree with Translate.
However I'd say that to another person and not directly to the subject especially in a speculative way. i.e talking to his boss or some other coworker I'd say:
Creo que él debe tener mucha experiencia después de todos estos años de trabajo.
Creo que él debe ser muy experimentado después de todos estos años de trabajo.
This is a compliment to the subject but the sentence is directed to someone else.
To say it directly to the subject I would not use the speculative sentence but instead an affirmative one without debe.
Tienes mucha experiencia después de esos años de trabajo. (You are very experienced after all those years of working)
This last one I think is more of a compliment than the other because I'm stating the fact, while using "debe" or "debe de" could have all the other meanings you described in your question.
However since the tile of your question is "using You must be in the context of a compliment" I'd say it like a speculative/question.
Creo que debes ser muy experimentado después de todos esos años de trabajo. ¿Cierto? - I think you must be very experienced after all these years of working. Aren't you?
Creo que debes tener mucha experiencia después de todos esos años de trabajo. ¿Cierto? - I think you must have a lot of experience after all these years of working. Don't you?
I feel like saying it in question form is more polite and would make a better compliment which is what you want to accomplish.