I don't doubt that there is much to be gained from extensive and intensive training in Gestalt therapy, as there would be in a number of other theories and methods. However, there is only so much time that one can spend in training and still eat, so compromises have to be made.
This may be a misreading on my part, but here it is . . .
You seem to be saying that nobody really ought to borrow particular Gestalt techniques (e.g., two-chair work) uness he or she is a full-blooded Gestalt therapist. If I misjudge you here, please accept my apologies in advance. If on the other hand this is more or less what you believe, try the following on for size:
Until you have had formal and certified training in behavior therapy, you really ought to refrain from treating behavior you like differently from behavior you don't. This, after all, is differential reinforcement, and without extensive formal training in the theory and practice of operant conditioning it is not likely to be done well.
What this reminds me of is my sense that this country has gone bananas over credentials, and has forgotten all about things like basic talent and intelligence. Nobody is supposed to be able to blow his nose any more without a Certificate of Intermediate Noseblowing Proficency from some accredited organization.
And when I think of people who, were they still living, might share my feeling that we have gone off the deep end, one of the first names that comes to mind is that of Fritz Perls.
So let's get back to the spirit, and not just today's received doctrine, of Gestalt therapy.