With the hardware that comes with a Kahler it will have a much lighter tremolo response than a Floyd. But if you want it to respond more like an original FR bridge you can order some harder tension springs from Kahler to use with it. As far as the tone lost....we can debate different bridges and tone all day long. ANY tremolo that replaces a hardtail system will affect the tone and sustain. Just as any amount of wood removed will have an impact as well.
The Kahler Hybrids DO beat out the Floyd Rose in two categories:
1) You can palm mute and play more normally without pitch issues, and double stop bends only cause a small amount of pitch movement on the bridge--more like the way a strat tremolo would respond.
2)You can lock down the Kahler with a little set screw in the back of the bridge so it can function as a hardtail.
The wood removed is very small compared to the big hole you need for a floyd.
I still say that for a regular-style Les Paul (i.e. anything other than a Schon or Axcess) your best bet is the Kahler over the Floyd.
If the sustain becomes an issue, then just drop a Sustainiac in the neck and you can have killer singing leads all day long :)
