I have done the bolt mode to a GX and a NX and they still ended up shit shifting. X01 is also twice the price of XT and I have said X0 is a a flawless group. I've owned/own SX, NX, GX, X01 and XX1.
How many km's a year do you put on this drivetrain ? If you are putting 3000 mountain kms on a GX drivetrain a year and its lasting, that's great... but in my experience on several occasions with mine, my 2 boys and replacing my 2 boys broken ones, GX and down are shit groups that will cause shitty shifting in one way or more at an early stage, whether it be looseness, bad seals and shims, add some mud, dust and even the occasional rock or stick.
If someone is doing 500 genuine mountain kms a year and saying their GX/NX is great, well that's all it's good for