Your stock Stella will be just fine on low octane during break-in. Some folks run high octane for the quality, not necessarily for the octane boost. People who have modded engines often opt for the octane increase. If the extra buck makes you feel good about the gas you're putting in it, good--but don't feel obligated to put hi-test in it.
Go to www.stellaspeed.com
and do a search on "octane" and you'll get a ton of responses...mostly along those lines.