I have a new Schecter Hellraiser Extreme that came with stock 10-46's. I prefer a hybrid 9-46 (only the thinnest 3 strings are different guage) -to bend a bit better....
Is that minor enough change in guage that I DON'T need a new setup? It has a Floyd rose and I don't want to screw it up...
Due to the difference in total string tension, you will have to reconfigure the springs in the bridge so that it floats in the same position as it does now, so that your action and intonation is unaffected by the string change. This could take as little as a change in the angle in one or two strings, by moving them from different hooks on the anchor plate, or holes in the bridge block.
Since you aren't changing the gauge of the wound strings, their intonation can be expected to remain good.
The intonation of the unwound strings is not affected by a change of gauge (if the strings are exactly of the same material, the action is the same, and the instrument is tuned to the same pitch). This is because a string of a given length, and fixed material, whether it is thick or thin, requires the same amount of strain (fractional elongation) to tune to a given pitch, and the resulting stress (force per cross-sectional unit area) is the same. A thick string has more tension because it holds the same amount of stress multiplied by more cross-sectional area.
A truss-rod adjustment is also unlikely to be necessary due to such a small change.
You should be ok. Worst case you may develop some slight fret buzz. It really depends on your guitar. You can always switch back to the heavier strings, if it doesn't work out. Also, you may need to adjust the Floyd Rose bridge slightly, but you should be able to do that yourself.
