so guys have a xt double up front running with kmc 10sl chain and sram x9 type 2 mech.
when in 2nd to biggest sprocket (34t cassette) the chain is always trying to drop off 38t front ring at the point where the 3-4 smaller teeth are for improved downshifting. the only thing stopping it happening is the front mech.
it also happens on largest sprocket so badly wont work basically.

anyone else had this and would a dyna sys chain be better????

Sounds like there is something hinky going on with your chainline.. I have the exact same setup (XT double, X9 Type2, KMC chain and 11-34 cassette) and it’s never missed a beat in any gear.

Not much help I realise but at least you know it’s not the component combo that’s inherently at fault I guess.. 😉

Edit:
Oh hang on, just re-read your post.. you are trying to use the top 2 sprockets while on the big ring.?
That’s kind of a no no, anything other than a spot on chainline will give you problems in that combo.

I can get away with big ring/2nd biggest sprocket but haven’t even tried the big-big combo as it was drummed into me as a boy not to do that or I’d die.!!! 🙂

i did wonder but chainline looks ok. custom built enigma frame specified with double chainset etc