x-over resistor replacement query

Freschie,
There is no direct answer to your question. If the resistor is in the tweeter pad or baffle step, changing the value will change the volume of the tweeter, so your speakers character will clearly change, If it is impedence compensation, it will change how much your impedance peak is lowered, depending on frequency, you might or might not notice, if it is in a notch filter, it would change how much peak is reduced and also would be audible. As stated by others, without taking considerable measurements, I would suggest that you follow the original design.
I hope this helps, Tim

Regarding the Caddock metal film, probably not a great idea to replace a 10W resistor with a 2W one. Depending on where it is in the circuit it may be fine, but then again may not.

There are a few 11ohm options, the Dueland and also Parts Express has the inexpensive sand cast inductors in 11ohm. You can also 'make' 11ohms as mentioned, but series or parallel connection. The Parallel option would be better because you also get more power handling that way.

Vapour1,

depending on the series or the addition of a heat sink the Caddocks can take 20w or even 25w so shouldn't be a problem.