I don’t know if it’s the shape of my ears but I tried Atlas in store today and experienced a really weird type of driver flex. Whatever way I tried to plug it in my ear hole, it created a super strong vacuum and there was almost NO sound at all! Literally! When I pulled them slightly, sound reappeared, but the same time I also lost seal. I tried for almost 10 minutes and other tips, but I could only listen to them by pressing my fingers on them. The strange thing is, exactly the same happened when I listened to the Vega and (!) Comet which were lying right next. Any other (CA) IEM I could listen to normally, only the CA dynamic drivers had this weird phenomenon in my ears. I own IE800, which are dynamics, too, but I never had such problems.
Yeah I am experiencing driver flex too. I didn't know about this phenomenon being linked to dynamic drivers until recently. Did read about it but never experienced it until now. Mine wasn't as bad as yours. I can still get a seal when pressure equalised. I am using both the Final tips and Spinfits. Have been interchanging between them. One thing for sure, if I wear it cable down the weight of the cable would pull the Atlas down and loses seal. Wear it cable up is much better but seal wasn't as good due to the design of the IEM. So I followed @Hawaiibadboy and @Colors which is cable down but route it over the ears. Its dorky (LOL) but excellent fitting for me.
However I am a bit concern with the cable strain relief though. I don't think its bad but just a thought.
I did found this link which seems promising.
http://snext-final.com/en/products/accessories/detail/earhook.html