After reading posts here about the improvement Sonicaps made in several members' speakers, I decided to give Jeff a call. He suggested that my Soliloquy 5.3s would particularly benefit by running his second gen 0.1uF sonicaps in parallel with replacements to my stock tweeter crossover caps. I followed his recommendation, received the caps in a few days, then had a local tech install them (took him about 90 minutes).
At first, I noticed a subtle improvement in my speakers at best... it wasn't until at least 50 hours that the new caps really began to show their stuff. Now, after almost 150 hours, I believe they are fully broken in, and the improvements are anything but subtle. The Soliloquys are fine speakers in stock form, but the Sonicaps have really improved their dynamics, providing deeper bass, increased detail (I can now clearly hear a marimba that I never knew existed on a familiar recording) and nice 3D soundstage expansion. I'm pretty amazed by how much these little caps have transformed my speakers. The total cost of parts including shipping was about $85, and the install about $60, so for a total of under $150 it is unquestionably the best upgrade for the money I've ever made.