ANC earphones are not designed with maximum sealing in mind(sometimes intentionally). Doesn't matter how plug and ear canal is tightly fit together, if what is suspended in the middle was a pipe with open ends.
ER4SR is the most classic/standard Etymotic model currently sold, other models complementing in both direction of prices. Perhaps more important than tip selection is correct insertion, or Practice and patience, which is unbelievably the exact wording used in their instruction manuals at least for my ER-6i. It is definitely not the healthiest earphones in the market.
I hear people sometimes use Etymotics with Comply tips. Wouldn't that create the same seal as using WF-1000X with Comply tips?
Also do you have a recommendation of an Etymotic IEM model plus a tip I can try for maximum effect