I think if you prefer the Klipsch sound then a Klipsch bookshelf speaker might be the best thing for you. The Hsu CCB-8 looks awfully promising though, but it will likely be a bit more neutral then your Klipsch speakers, so maybe not the type of sound you would prefer over Klipsch. If your left and right fronts are going to be Klipsch, so should the center speaker; you want the front stage to be timbre matched, so it should be from the same product line. If you are thinking about trying a different sound, maybe a Hsu CCB-8 set is the ticket since that design bodes very well for a cohesive sound everywhere in-room. By the way, the CCB-8 has been delayed a bit, so they might not be available in late January as the product page predicts.
If you want a substantial upgrade within the Klipsch family, try to get three of
these while they are in stock (this product line is being clearanced). It has very good off-axis response and should have an extremely good dynamic range for a bookshelf speaker. I would expect it to be much better than your present speakers. Right now it is on sale for a great price.