There is no license key required to use DFS band, they will be available for free, you would need to upgrade to latest firmware once we receive approval. We are currently pending by IC regulatory body approval, we expect to be granted in early Q4 2018.
In regards to Tx Power configuration, it is bound by regualtory, APTC etc, we have detailed community post here:
The rules for operating in the 5150 MHz to 5250 MHz band are provided in http://www.ic.gc.ca/eic/site/smt-gst.nsf/eng/sf11294.html. This band requires a license in Canada. The technical rules are similar to FCC U-NII-1 band, with maximum 53 dBi EIRP for PTP applications. Like U-NII-1, there is a very stringent limit on out of band emissions (OOBE), set at -27 dBm/MHz. Meeting this OOBE requirement is a challenge for any manufacturer. The power limits for PTP 550 are set by the need to meet the OOBE requirement, and not the 53 dBm EIRP limit.
We can't answer for other manufacturers, but it seems very unlikely that competitor products would be able to comply with the SMSE-013-17 requirements while transmitting 1 W into a 23 dBi antenna.
I'm never 100% confident that I'm reading the FCC test report for Mimosa B5 correctly, but it seems to me that in the U-NII-1 band, the results were measured at transmitter powers of 15 dBm (20 MHz) down to 5 dBm (80 MHz). Perhaps another Forum user could confirm?
After learning here that the PTP550 was crippled in the US (and probably Canada) to not allow high-gain antennas, I went back to the Mimosa forum to verify their EIRP limits. They are approved for +40 dBm EIRP (i.e., +15 conducted and 25 dB gain on the B5, or based on the antenna on the B5c) on U-NII-1, and +53 on U-NII-3 (where OOBE is looser). We're starting a project that needs about 70 such radios, hops up to around 20 km long. Guess which one we're going with.
(I doubt Cambium's OOBE is actually worse, but they seem to have crippled the 550 in order to protect the 670. Not even the same market.)