My experience with EtherREGEN was a mix bag as well. It did more harm than good in my system and I end up moving away from it. When it first came out, there weren’t many options to tweak Ethernet so many reported positive feedback. IME, the impact of FILTERS and Switches greatly varies depending on what’s ahead of these devices. If you were using a high quality streamer, their impact may not be profound as opposed to someone using a Nucleus or iFI Zen.
I keep an open mind when it comes to Ethernet tweaks and believe their is no substitute for trying them in your system to truly understand their impact. Like you, I got done tweaking my Ethernet chain when I switched to Telegartner M12 Gold Switch w/JCAT LPS. Further, my switch and router are grounded with a pair of Entreq Macro Ground Boxes, the additions of grounding boxes was like cherry on top :-)