I've got big ear canals. I bought the Bluebuds X and, unsurprisingly, I lose the seal rather easily, even with the largest of the provided tips. I tried the Comply foam tips (Tsx-500, Tx-500, S-500), with even worse results: Tsx-500 and Tx-500 barely provided a seal and were ruined in a couple of weeks (I was going to the gym daily, sweating like the proverbial pig). As for their "sports" model, the S-500, for some reason it is smaller than the other two, even though all were labeled as large: I couldn't get a seal at all.
I thought about buying custom silicone tips, but I'm afraid those will make the Bluebuds X very hard to swivel (I wear them with the cable over my ears, most often, but need to switch to downward cable when I get a call, to move the microphone closer to my mouth).
Any tip on tips?