Yeah it should have some tiny touches like the 335i has compared with the 330i and 325i

Sounds nice but we all know Mercedes never works in that mannor.
It`s either the signature design itself or it has been modoified with a sportpackage. The 600 is the end of the "normal line" (before we reach the more powerful AMG S-Class models) I don`t see the trouble in raising the bar with the package to bridge the gap between them.
Or maby I`m asking too much.

Yeah, just leave it as an option is the best, the preference of the package would really depend from owner to owner.

I'd put it in the S600, or any S-Class for that matter, because I want to look a little different than the rest of the S-Classes running in the streets.

The people who buy the S600 tend to usually be on the conservative side and I guess they like the S600 just the way it is. No need to attract attention when you want to do the exact opposite: ride in gracefulness and comfort in a car that just looks like any other S-Class out there.

If I was shopping for an S600, an AMG body kit is a must. I like the standard S-Class, but with the AMG kit....