The Primus 360 measures very well, and is generally regarded as punching well above its weight. The Beta C360 is also a highly regarded center channel. The Klipsch RP series has also received nice reviews, and they're more efficient than your current Infinitys, so they should be able to play louder with the same amp.
You'd be going from three-ways to two-ways, but there's nothing inherently wrong with a good two-way design, though with a two-way center channel you'll have a smaller sweet spot than with your current three-way.
I imagine you'll hear a difference, whether or not it will be better I can't say.
HT: Sony 940C, Oppo 203, Harman/Kardon DPR1001, Infinity Interlude IL40 x2, Infinity Interlude IL36C, Infinity MS-1 ii x2, Infinity MSW-1
Computer: Elac Uni-Fi UB5 x2, Elac Element EA101EQ integrated amp, SVS SB-12NSD
Dedicated 2-channel: Infinity Intermezzo 4.1t towers, Bluesound Node 2, Emotiva PT-100, Crown XLS 1502, Furman PL-8C