First off I will shed a little light.. I have experience with just about every cap, minus the Duelands.. I can say easily Sonicap standard Gen II's are not the end all be all or near it, they do cost very little money though, I mean a 1 uF cap is what 7 bucks? They are decent, but much better in some electronics than speakers from my experience, however even in components will be handed a beating from some of the better caps.. They are very linear, but slightly dry, and are no question flat... But they also seem to exhibit a slight over raw enhancement, much like Dynamicaps, which are even worse in some critical applications if you don't want a lot of added peaks and valleys in your overall sonic soundscape don't use sonicaps or dynamicaps...
This is just my opinion in the limited applications I have tried... The mundorfs are Great, but still slightly overpriced, a more neutral and capable cap to an extent in my opinion is the Cardas golden reference, and the Sonicap platinum, but both in very small values and are pretty pricey... They take about 400 hours to open up, I ran them in a hi power TUbe application for about 2 weeks straight with cheap 2 dollar tubes to burn them in, and WHAT a difference.. Speakers will NEVER burn in a tube like power electronics until probably even 1000 or 2000 hours so get ready :-)