I know from experience, but I also know a few guys who have send their ECU to Guhl and received within 3 weeks.
I asked this guy not to alter safety settings like rev limiters or top speed limits. I know Honda takes safety very serious and you never know when you have entered the not-save-area.
The only thing is you have to visit him with your bike. He wants you to take a test drive.
It turned out Honda has a lot of different ECU versions, and every version has its own data order. It takes a lot of time to adjust all data, the test drive will tell him all is fine. Its not his job, just hobby.