Can elaborate how you felt compared to the rest you tested?
IMHO I am a newbie,(All tested using same song and volume)
Shure SE215 LTD Good bass, but mid and low wise not balance. The sound too warm for me but I really like the fit but westone IEM fit still the best.(Came from westone, honestly this one feel dull)
UE900, This one i feel lack in most bass,mid and low.(Totally not my type)
FTX90, Love the clarity with good mid and low. But I feel the bass just not enough.(Almost end up purchase this).
Then this CKS99 I feel the bass more punchy but mid and low still good and clear as FTX90. This CKS99 what I found have a signature sound that makes me want to listen a song that usually I don't listen

.
But I still do hope they will build IEM fit like westone. But for the price of CKS99, I feel very worthed.
If got more money will buy Westone 4R

(I Itchy hand tested it and blown away with the sound, but the price not for my budget LOL )
Westone 1 vs CKS99 :
- Seperation and clarity (Westone 1 Win)
- Bass (CKS99 Win)
- High Bass (CKS99), on some song Westone 1 bass distort.
- Sound Signature (Draw)
- Ear Fit (Westone 1 Win), Wearing westone 1 IEM feel like not wearing earpiece

Damn Comfort!
Music I listen like MatchboxTwenty,Bob Marley,Adele,King Of convenience.