You're wrong, 4.5 console don't need to patch Nintendo DS profile at each restart (with blue card).not true if you keep the 3DS in standby mode when not in use. If you fully switch off your device you must boot again via the profile exploit (firmware 4.x) or the Mii QR scan on 9.2 (if ever released)
Only need to Go to "Console Settings -> Others Settings -> Profile -> Nintendo DS Profile" to boot in GW mode.
About 9.2 max compatibility, we don't know if QR Code must be done each time after shutdown console.
If proceed like "Ninjhax" exploit, QR Code + network need to be done each time...