True, just leave the wave-y bit out and it's just an ordinary Slaanesh symbol. Maybe if you are crafty fill it with clear resin or something too.
The Keeper is pretty crap for 40k unfortunately. If you don't go first it'll just get blasted off the board turn 1 by your opponents anti-tank. There was hope that the Aegis could help out there but with just a 6+++ I'd rather take any of the other options, really.
Shalaxi Helbane isn't really convincing either since she relies on rolling 6s or just generally well on the damage stat of the spear. S12 is overkill against most characters too.
The only great thing about her is the 6" pile-in move TOWARDS CHARACTERS. So if she miraculously survived long enough to make a charge you can declare some near unit and a character within 6" as your targets, then charge the random unit and then pile-in away from it into the character you want to kill.
Considering that any KoS will be very low on wounds if it gets to charge something I think I'll prefer the regular Keeper with Sinistrous Hand and the relic Witstealer Sword though so it can heal itself up to get shot at another day.
Syll'Esske is as we've already known just awesome and I'll definitely be taking them at 210p.
Contorted Epitome seems great too. No point value for that one yet but as character with <10 wounds, a bunch of attacks and still the Herald aura (so it actually has S6 attacks!) it's basically another no-brainer for me. Between this and Syll'Esske I wonder why I should ever take a regular Herald ever again unless I'm low on points.
I agree on the Keeper vs Shalaxi being forced to take the Aegis gimps her and Soul Piercer isn't worth it over Witstealer. That said you do have the option of popping Warp Surge if you don't get turn 1 or you can always Deepstrike or Summon her. Alhough anything other than Summoning is going to be expensive in terms of CP.
Syll'Esske is an auto take in my opinion at 210 pts.
The Contorted Epitome I'd always take one, most likely two in my lists. No reason to bother with the Index Heralds now. I can't believe they made the thing Calvary. The Contorted Epitome is as fast as a winged Daemon Prince, has character protection, and can prevent any unit including flyers from falling back within 6". Is a Psyker capable of casting to powers and does 2X S6/AP-2/Damage 3 attacks and 8X S6/AP-1/Damage 2/Wound rolls of 6+ count as AP-4 attacks hitting on 2's. Nevermind, its +1S aura, and 2+ save vs mortal wounds. The things a beast. Its basically a flying Daemon Prince with excellent bonus abilities. You can also proxy the mirror from the Endless Spells kit as a second Contorted Epitome.