The ESP Guitar Company

It sounds like a gradated shim would be the fix for the action at the nut. If your tech used paper for the shim, I'd probably find a new tech.

The "resonant peak" seems a bit hogwash to me. Especially considering the JH-600 isn't Japanese, it's Korean. It's true that some guitars can have dead spots caused by the resonance of the wood, but you find that more in hollow and semi-hollow bodied guitars. I'd lean more toward a fret leveling issue. Instead, I'd try a simple fix like replacing the clamping block on the G string of the Floyd saddle, or changing the string gauge you use for the G first.

Thanks for your opinion. I'm waiting for new techs and this local luthier to answer, (worked on EVH himself and Fender, etc) but no one has given me their opinion since I've contacted them =/

Actually, no for sure this is really bad. I just discovered the D string is high about 8c at the 5th fret. This mean's i can't possibly tune my D string to my G string! It reads in tune open but I have to tune the D string flat to make it in "tune."

I think this nut shim totally screwed up my guitar

Have you tried adjusting the intonation at the bridge?

Yes. I actually moved the saddle back and the string while intonated at the 12th fret is not changed at the 5th. Instead of reading G it reads +5 cents so it won't tune with the neighbor G string! 
This is some bad work man. I brought this guitar in to make it play better not worse.
When I had brought this guitar in, I had pre intonated the guitar and had no issue . Now it has an issue on the D string

Ok guys, one of the major problems has been solved. I was told that DR strings do not intonate and you know? They were right. I trusted this DIMEBAG string and removing it and putting in a ghs string solve the problem.

I still need a way to fix dead sustain on G string and some fret buzz, but at least its not a total emergency now.

 Raise your action at the bridge 1/4 turn (loosen all the strings first and pull the bridge slightly away from the posts to avoid damaging the Floyd edges.)

I didn't realize they made an LTD with the Kahler.

If you raise the action at the bridge a bit, you may reduce the string buzz and gain some sustain on your G. You could also try adding a bit of relief to the neck (loosening the truss rod), but you said the action on the higher strings near the nut are already higher than you prefer.  My guess (without seeing your guitar) is that you're getting the buzz on the higher frets and that slightly raising the action will solve that issue.

I'd still recommend trying to raise the bridge a touch. Raising it at the bridge end will make the strings higher at the high frets and less so at the nut.  At this point, what's the harm? 

I'd also recommend you try a different brand of strings than whatever it is you're using now. I don't have tons of experience with Kahlers, but I've never had this much of an issue getting them running.

A fret level and recrown might be the solution, but that doesn't mean you can't make it playable in the meantime.