23mm's will make a small difference, a little more speed, as well as a little rougher ride.

While it is all about the engine and your bike is *fast enough*, I'd keep my eyes out for a good deal on craigslist. If a new ride inspires you to spend extra time in the saddle, it's well worth it. I WOULD NOT spend $2-$3k on the latest model at the bikeshop, but bikes often sell at 1/4 to 1/2 of their MSRP. Ebay is another good option, especially if you sort results by distance and find something you can pick up. Don't upgrade immediately, but keep your eyes out.