It's way better to install the proper firmware.
For example, C6502 has a barometer, but if you install C6506 you will lose the support to that function, since C6506 obviously doesn't have the proper driver. Also, you can brick your device if you lose a driver that is essential to boot.
Finally, some ROMs demands an unlocked bootloader. So, take care and remember to backup your TA partition before unlocking, or you'll lose your DRM Keys and your Bravia Engine forever.
For example, C6502 has a barometer, but if you install C6506 you will lose the support to that function, since C6506 obviously doesn't have the proper driver. Also, you can brick your device if you lose a driver that is essential to boot.
Finally, some ROMs demands an unlocked bootloader. So, take care and remember to backup your TA partition before unlocking, or you'll lose your DRM Keys and your Bravia Engine forever.