(...) Savoy often had to manoeuvre between France, Spain and Austria, which could backfire, since none completely trusted them.
(...) If I may turn around your final comment, "Savoy often had to manoeuvre between France, Spain and Austria, which could backfire, since they could never completely trust anyone of these powers."
I'd argue both are true and strengthen each other, since they tend to confirm each other.
Having to trade Sicily for Sardinia, is losing the big price, they didn't necessarily want nor realistically could hold, for something less valuable they were able to hold. IMHO a painful loss, but I agree realistically it wasn't that bad; perhaps by this point the ruler of Savoy was content, that he stayed a king.
I also don't dispute, that given the fact, that other stronger powers were also interested in the duchy of Milan, Savoy never had much of a chance to gain the entire duchy.
I also fully agree, that Savoy retaining their independence, arguably is a rather undervalued achievement. Something another less optimal placed medium power, Lorraine couldn't; though dynastically speaking being able to inherit the Austrian Habsburgs and obtaining Tuscany isn't too bad.
Savoy OTOH stayed around, their ruler even rejected to exchange Savoy-Piedmont for Naples-Sicily (it was proposed during negotiations, before the war of the Spanish Succession); though to be fair to Lorraine, that duchy had been occupied by the French on more than one occasion (that drove them straight in the Habsburg camp).