Wow, I'm not sure that we've ever had so much agreement in a single thread on here .
In any case, I do have a few more comment.
Simichrome works in two different ways: it's both a mild abrasive and a chemical polish. The abrasive means that, if not used with care, it can cause undue wear on cases.
While I often do use it on gold filled cases, I only do so with just a very light touch. Otherwise, one polishing can cause an equivalent to years of wear through normal handling.
Also, if you're dealing with silver, think carefully before you polish it. A nice even gray patina can add value to a case, and is probably best left alone. A mottled black or brown case will benefit from polishing. Even so, though, having engraved designs that are highlighted by a nice gray or black patina in the crevices will look better(and probably be worth more) than one that's completely dazzling all the way through.
Remember that patina takes years to achieve and seconds to destroy.
Also, if you're able to do so, it's best to remove the movement from the case before polishing.
Adding to what Ben posted, the chemical cleaning effect of Simichrome will take the varnish off of your dining room table in seconds, if drops happen to spill when polishing or fly from the buffing wheel. Choose an appropriate work area.