I run 3 Mimaki JV33's and a CJV30 in my studio. We have the white and silver configuration in 2 of our JV33's and my CJV30. Im also a dealer for Mimaki and the ES3 inks do take longer to run. The profiles are set to print slower with the ES3 inks than with the SS21 inks. Im actually about to switch back one of my printers to the SS21 ink because of the speed. Also, with the existing profiles that exist for the ES3 inks the reds arent quite where the reds are with the SS21 ink.
As far as changing over the SS21 machines to the ES3 inks.Or changing the inks configuration over to use the white and silver its not hard at all. It really isnt a big deal. Its really depends what your existing ink config is now. Feel free to answer this post with which config you are now and I can walk you through the steps.
As far as the quality of the silver ink. Ive been very happy with it. We run it a lot in our studio. It looks very much like offset silver. I will say however if you either laminate it or uv coat it, or reverse print it on clear material. The silver will be toned down to almost a gray when seen through lam or clear. my best pieces are those printed on matte or satin substrates. Hope this info helps.