I tried the Final Audio ear tips recently, as I was getting sensitive from using the foams too much over the weekend.
I was surprised that they fit! I used the large that my wife doesn't use on her E2000s. A few things though, they sometimes go in too far, and when that happens, I lose my seal. I want to say I need a bigger pair, but when they seal they feel just slightly too big, so I am not sure if that is a good idea.
They are also just a little too loose. I keep losing one side in my ear if I don't pinch it to the earphone when I take it out. It's a little annoying, I am thinking of adding some of that thin white plastic sealing tape they sometimes use for water pipes on the nozzle to make it just a little tighter.
Anyways, it's like putting a breathe of new life in my ER4XRs. These days, the extreme isolation was stopping me from using them, since I stopped commuting on a noisy train and my wife is chatty and gets mad when I don't answer. The isolation now feels about the same as regular IEMs, and they are less painful to put in and take off than they used to be.
Thanks for the suggestion!