I'm a first year beek as well, so take this with a grain of salt, and please correct me (anybody) if I'm wrong.
My concern in splitting now is that they won't have time to build back up before winter. I know your winters are not bad, but who knows what this year will bring. Even so, you might have a dearth in the fall and they could well starve in even a mild winter.
You could always give them more room now to limit swarming and reduce the size back down as the queen slows her laying later in the fall. Maybe give her another medium now and when she starts to reduce for winter cluster you can combine the mediums so she has enough winter brood room and plenty of stores. Freeze whatever stores don't fit and give them back to her if needed over the winter ( in the event you have an unseasonably brutal winter).
If you are having swarm issues, I'd forget about honey collection for this year and solve the swarm issue.
Just my $.02
