Believe me... I certainly don't mind the fact that you have taken the time to thoroughly service and overhaul my El Primeros and VJ23! It's good peace of mind for me... Knowing that everything was cleaned and oiled properly, mainspring changed, etc., parts inspected for wear/damage and so forth...
Is your way the right way? Well... For me, yes, it is. As we both know, the EP400/3019 is an odd creature, and there are some graphite lubricated points that shouldn't be cleaned (as per Zenith). So, the only way to properly do the job is to tear everything down... Replace the barrel/mainspring as recommended, and lubricate with the correct oils...
So... For your expertise and knowledge, I am willing to pay more, and willing to wait a few days longer for completion. Knowing that my movements have been thoroughly gone over, inspected (and signed off with a clean bill of health) is worth the price of admission in my eyes...