[f5fstop]

Sounds more like an intermittent open in the electrical system. This could be caused by a bad connection on the battery's positive or negative terminal, or the main ground from the battery.
Reason I say this is not based on any fact, other than if the vehicle can pull the amps to start, there are plenty of amps to keep the clock going. (Starter draws amps...radio draws micro amps.)
Another reason is you say it hesitates; therefore, I'm thinking the hesitation is due to a drop in the amps being drawn by the starter, but not long enough to actually stop it from spinning (or gives that appearance), but a split second dead circuit (positive or ground), will blank out the radio clock.

I would take a close look at the two main grounds from the battery and make sure they are tight. One ground is in the engine compartment, mounted to the LF inner fender just behind the battery. The other ground is in the engine compartment, left side of the engine block in front of the starter.

This may not be the problem, but that is where I would start; especially if it is intermittent. Intermittent problems are a SOB to troubleshoot.

Replacing a battery without first having it tested is an expensive, possible non-repair. If you wanted to replace with an Optima, I would agree, since they have a great reputation, but if you don't want to, or need to (still under warranty), then why pay that cost, and it might not be the problem.