The quality of your speakers is the most important aspect of the sound of your system. However, the quality of a speaker's sound is mostly a subjective matter.

For my money, the Reference Series Paradigms are well worth the extra cost. You have to make your own judgement on that, though. Listen to them both, and then decide. When I heard the difference between them, I made the decision to buy my speakers in stages, rather than all at once.

I couldn't afford to buy 5 channels of Reference all at once, so I just bought the front pair. Later, when I could afford it, I got the CC. I'm still using Cambridge Soundworks Surrounds, but will replace them with Paradigms eventually. It will take longer to do it this way, but I get the pleasure of hearing the vast improvement that each speaker purchase confers.

Like GregoriusM said, Listen, listen, listen. Not to us, but to the speakers.