....Hmmmm...MEST and LX are VERY different beasts
My current IEM's are CA Atlas, LX, Mest and Sony IER Z1r. I love em all and they are keepers for me for now. In terms of "all rounders" - ie an IEM that I can just throw on and be confident its gonna play nice with any genre I throw at it...I would give the crown to the Sony. The MEST...is just a special gift when I want a GREAT detail treble, and just awesome "holographic" euphoric experience. It is a V/U type tuning, but I wouldn't call it a TOTL bass head experience, Like the LX is. You have the Atlas, as I do, and you are thinking of the LX... so chances are we have similar tastes. And even though Mest is not in that bass league of the LX (Mest EQ's really well though)...I LOVE IT as it is such a great compliment to my other units. Look...nothing I have tried is gonna give you that detailed SLAM of the LX...it is just perfect when you are in the mood for that. But...given you already have the Atlas (no slouch in the bass SLAM dept)....if you want some great variety...I reckon go the Mest...not to mention the $$$ difference. One thing with the Mest though....tips. Of course tip fit is crucial with all IEM's, but
especially with the Mest.
If you are a foam fan (I use foam with Atlas, silicone with the rest)...I would not suggest the Mest. IMO it just kills what is special about the Mest...makes it kinda generic. But, if you use a silicone that isn't a great fit with it, it can sound like a treble mess. For me, the key was finding the perfect fit silicone with it. For me, that ended up being the Spinfit Double Flange. Once I worked that out, I was in heaven with the Mest. It allowed for deeper insertion, and more shell to ear contact. Of course, double flange aint for everyone...Hope that all helps mate. Good luck!!!