PS: I'm told that Sky use it.
Do they though? Apart from that one article (where its unconfirmed), there's no mention anywhere else and I don't think anyone has ever seen any evidence of it actually in use.
We’re still awaiting confirmation from Sky but we believe this can be employed by ISPs that use Broadcom’s DSLAM network devices inside telephone exchanges.
There seems to be little information about
Nitro Nitro is one of several competing incompatible proprietary extension approaches that were developed to increase performance of 802.11g wireless devices, such as 125 High Speed Mode from Broadcom,
There seems to be a French ISP who may have used it - See
Freenaute to be able to offer upto 28Mbps.
Although they mention the BCM6348 I cant seem to find any mention of it on the Broadcom site nor in the 6348 datasheet. The only English reference I can really find is in relation to Broadcoms NitroQAM for wifi chips.
btw if it is proprietary, then like you say it would mean that both DSLAM and modem would have to be BCM. Sky LLU MSANs are mostly Alcatels which irrc use BCM. Although sky hubs for FTTC have BCM chipsets, I dont think all their adsl2+ routers do/did.
I can't see BTw as eager to use it because they have too many DSLAM/MSANs that arent BCMs.. plus unlike Sky they have absolutely no control at all over the type of modem/routers that are used by the EU.