I have the universal version and have almost no complaints. Sound isolation on them is amazing, best I have ever had for an IEM. My complaint is that the right one tends to slowly come out over time but they're universal so I'm not knocking them for it. Plus it also happens when I'm at the gym or working out in general.
Beyond that nitpick, I love em to death. I have the 3rd Gen and again, no complaints. Love the sound out of it without any eq adjustments but I have adjusted the eq to add a little more bass. But if I had to use them direct as is, I wouldn't mind. They're definitely in the neutral camp.
I also just received the 4.4 balanced linum superbax this week since they finally had them in stock. I tested them out without any eq adjustments, just direct from the source and I have to say they sound better. The single biggest difference is just a wider soundstage. It's still small compared to my isine 10's but there's more room for instrument seperation. The 3.5 stock cable, which is also a linum superbax, is still great and I want to say the difference is about 10% or so between them but it's more than enough for me to keep the 4.4. I have the zx300 so the balanced out is better than the standard jack anyway.
I know cables is a contested issue here but considering I adjusted the eq on the balanced jack and raised the 1k through 16k frequencies without adding any sibilance I really do think the cable made them perform better. Without any eq'ing I simply noticed much better separation between instruments and voices.
My experience and even though I'm tossing percentage out, I didn't measure with any instrument to get cold hard data. Just going by ear and how it sounds to me.
I would have bought a cheapo 4.4 cable for it but I couldn't find anything that wasn't custom made due to the IPX/T2 connections. I bought a cheap 4.4 balanced for my isine 10's and again, worth the upgrade and that one cost 50 on Amazon. So I'm not saying spend 300 for the linum version but since they made the stock cable and they're soo light I never really feel the cable once I have them on, I wanted their product specifically. It's difficult finding IPX/T2 cables and boy, did I try.
Hope I gave you enough info to chew on.
To answer the main question though, I have the universal versions, somewhat small ears, maybe mid size but definitely not large and they fit amazing. The gym sounds disappear until any pause between tracks.
Once I can financially afford it, I'll be looking into reshelling them but that's a far future notion and I'd rather save up for a new dap, if anything.