Well..I'm replying to myslef as I did some looking around last night. Seems there is hardware available (in the form of a tuning chip) that will remove the speed limiter. These can be found by searching for "tuning chip for bosch performance cx" I won't provide any links because I'm not sure about the forum rules. They claim the speed unlimiter is not a hack or is it illegal. I just wish I could circumvent the dealer to do maintenance on the electronics.
Like you, I'm a DIY'er and like wrenching on my own stuff. Diagnostic devices are available for cars / trucks and even motorcycles now via OBDII connections. Having to find a dealer to perform software updates is a PITA. All the trouble codes are available via the Bosch ebike web site in addition to manuals FWIW. The 20 mph speed restriction is part of the motor vehicle code in the US and might be tied to the software availability or lack there of?