Yeah, Don Guhl does good work on the Gen5's... getting on the dyno would be your absolute best bet. You will need some kind of PCV or aftermarket fuel management system to have the bike dyno tuned. That's just what most dyno tuners require. I would get a PCV and get on the dyno then have Guhl flash the updated fuel map into the bike. You can then sell the PCV.
You otherwise do NOT need a PCV for a simple ECU flash, don't believe anyone that tells you otherwise. If you want just an ECU flash and don't want to travel or buy a PCV get with Shnitz, Nicks Performance, or EJR performance. ACE Performance is also really good. Those are going to be the best street tunes out there. And I would say SBU or EDR are going to have the best track tunes.
When in doubt... send it!