Your problem appears to be one of synergy. I think that Soliloquy and Silverline both build great products. I'm not sure they work well together though.
Why not try a more flexible sub, like a REL, if you really like the Silverlines? You can get a new Storm III for less than $2,000. Used RELs seem to sell quickly.
On the other hand, keep your sub and try out Soliloquy's monitors. I believe that their SM-2A3 model was designed by Dennis Had of Cary. The 5.0 is their newest monitor. Either of these can be had for around $1,500 new including custom stands (which should be considered part of the speakers). I don't see too many of these used. You can save some money buying Factory B-Stock.
I own a pair of Soliloquy 6.3 floorstanding models (as well as C3 center channel) and am quite satisfied. They probably don't image quite as well as monitors, but with frequency response down to 25Hz, I only use a sub for home theater. These actually don't take up much more floor space than monitors on stands, but they are more visually prominent.
Feel free to send me an email if you would like to discuss further or would like referral to Soliloquy's Factory B-Stock distributor.
Best regards.
Brady