The unlocked fimware only works on the Huwaei modems.
I have just had an FTTC instal today and fully intend to "monitor" the connection - I bought a modem on eBay in preparation .
With the unlocked firmware you can also stop BT access to the management facilities of the device.
With no problems it is obviously not "essential" but if the connection is not at the full 80 / 20 (or whichever package you have) you have no way of knowing if there is a progressive reduction of sync speeds for any reason.
Ex <n>ildram , been to SKY MAX - 15,225 Download
BE Unlimited - 21,000 Download 1,200 Upload,
Moved house, now BE Unlimited 6,500 Down, 1Mb/s up - gutted!
FTTC Cab enabled 30th July - expect full 80 / 20 - BT Infinity ordered, install date Friday 10th August! BT didn't turn up - now 17th August