Silver Wire

First, you need to know how to remove solder and resolder well enough to proceed.

I won't answer your question directly, because mine will be just another opinion. I will say you can't disregard the quality of the wire you're replacing. You want to be very careful not to replace wire with worse electrical properties than what you replace (e.g. resistance, capacitance and inductance). I'd strongly suggest you measure each wire you remove for all these properties and not replace them with anything that has worse values of these properties. What is worse? That might be a separate thread. We'll see.

dragu- I realize I misread your question a bit, but maybe i lucked out by still answering a related question. sorry.  i'll revise a bit ...

If I was doing what you're doing, i wouldn't care if it's copper or silver. I'd go with the wire that has the best of the electrical properties mentioned above. That would include the quality of the soldering. Also, if it was me i'd try to keep the gauge the same or bigger (if not too cumbersome) and if possible go with a wire geometry that might lower inductance significantly while keeping capacitance within reason.

I expect to have to learn to solder at higher temperatures. And to use heat sinking near heat-sensitive components on the crossover.

I'd expect the silver wire to have less resistance than the copper, but measuring first is not a bad idea.  

Some speaker manufacturers use silver wire in their speakers, such as Tannoy, which also uses silver plated copper wire.

Greetings Dragunski---

    I have a pair of DIY speakers that are similar to Legacy Focus in design.  The builder used stranded copper wire and they sounded quite good that way.  I re-wired them internally with the heavy gauge Anti-cables speaker cable using Radio Shack disconnects and this sounded better but I wasn't too thrilled about using the disconnects so I acquired 18 gauge wire from Anti-cables and crimped them onto the crossovers and drivers directly and this sounded much better; more transparent with greater detail and the soundstage was more distinct---image outlines were sharper and both lateral and front-to-back imaging improved. 

    I then acquired some vintage silver clad copper wire of about 16 gauge and this wire has been used in my interconnects, power cords, and speaker cables and it's excellent.  I happily sold my interconnects (Ridge Street Audio Poiema !!!, Granite Audio 470, and Nordost Quattro Fil) as well as several power cords (too many to list).  I've re-wired these speakers with this wire in doubled-up twisted runs (still only crimped on----I'm not to fond of commitments) and the upgrade from the 18 gauge Anti-cables is highly apparent.  First, the bass is much more solid, no bloat whatsoever and with texture that the other wires never even hinted at.  The top has air and ambiance that was also missing though I hadn't thought it so until I installed the silver wire.  And there is a presence or "there-ness"  that just sounds more real than through any of the other wires.  So, I can say that silver CAN sound much better than copper but it will depend.  If you're concerned about the top end becoming bright, then perhaps the Mundorf silver/gold wire would be a better option.  I don't know about its authenticity but I can vouch for the sound quality of the Mundorf 1mm wire sold on Ebay through Taiwan.  I've used it for power cords (4 runs per pole using the excellent Iego 8095 rhodium plated silver plugs) and am having a pair of interconnects built presently.  Hope this helps and good luck.