I am a NON Klipsch owner but have done a few setups for ppl using the Icon and Synergy series and I have demo'd the Reference series.
IMO the Reference series is definitely better, BUT if you are only buying the Front Tower speakers and are on a tight budget the Icon or Synergy are fine unless your an audiophile and looking for a great musical speaker. However if you are planning on a 5.1 or higher Klipsch system I would recommend the Reference series. The centers in the Icon and Synergy series are really lacking and have horrible bass response and sound best with an xover at 100hz which to me is too high The RC-62 or even the RC-52 is a much better choice for a center. The surrounds in the Reference series are also much better than the others.
I currently have a RC52 centre, Celestion F30 towers (10 years old), no name surrounds. Deciding on whether to buy a set of bookshelfs and surrounds to match my Klipsch centre or just gradually piece out a new speaker setup.