No, for exact timbre matching, try to find a Polk center with the same tweeter as in your R15's. 1 - 3/4" Diameter (1.91cm)
Dynamic Balance silk/polymer composite dome-shielded. Just about all Polk's tweeters are the same, as well as the efficiency, so you won't have to adjust the level of the center (as much). With the newer receivers, you can go with another center because of the control over the frequencies and level. Better receivers have parametric eq's to get the highs to sound similar. The BIC has a 3/4" poly dome tweeter rated at 90 db, which is right at the Polk level listed at 89, but they also have 6.5" woofers, which may overpower your front R15's with 5.5" woofers. With that center, you would need to turn down the level of the center for balance. You can mix and match, but in doing so, stay with similar tweeters like domes to domes, or horns to horns. Your center channel is the most important speaker in your setup. For $150, you cannot buy a better center than the BIC regardless of perfect timber matching. I'd even put it up against my $480 CSi5 Polk.