I'd be surprised if BTW are consistently throttling at the level you mention, as that would seem to break nearly every ISP throughput guarantee out there. Any more info on that? Sounds worthy of investigation.
Perhaps I was unclear in my use of the term "Throttling". What I mean is that BT Wholesale, at my Exchange,
will not sell any FTTP connection handover service above 330 Mbps. If you were an independent Reseller ISP and went to BT Wholesale and said "my customer wants a Gigabit connection", BTW reply that "sorry only up to 330 Mbps maximum is available here". Indeed some ISPs tell me that Openreach can only provide 300-ish megabits per second, because not everyone makes the distinction between Openreach and BTW clear.
So if one believes the "Everyone has to use BT Wholesale over Openreach" generalisation, then the maximum speed available where I live is around 300 Megabits per second FTTP. Because BT Wholesale presumably don't want to spend lots of cash on a Gigabit service for which there is insufficient demand. The local optical fibre network - the GPON - is able to sustain Gigabit connections but the "Handover" bandwidth at the exchange is limited unless and until there is an investment in new and better routing kit and/or Backhaul capacity.
So to most potential FTTP customers "300 is all you can get" is the End of the Story where I live.
But after some research I found that TalkTalk Wholesale had installed "Unbundled" handover equipment in my local BT handover exchange and were able to offer near-Gigabit download speeds. So I ordered from Cuckoo as a provider who resell - as you correctly described - the standard TalkTalk Business service, pretty much.
This has worked fine and I expect HomeTelecom service to be
technically the same. But I worry about possible less favourable terms in terms of hidden "acceptable use policy" usage caps and/or stuff like CGNAT shared IP addresses (though if it is the SAME technically I'd expect a fairly "sticky" Dynamic IP as it is presently). As a direct contract with TalkTalk Business is actually a tad
cheaper and also includes Static IP, I think I would find that preferable.
So basically, default FTTP where I live is 300-330 Mbps max, via BT Wholesale. It is
not that they throttle a Gigabit advertised service to 300 Mbps, it is rather that you can only buy the slower service in the first place...
... unless you choose an
unbundled handover provider at the BT Exchange - i.e. TalkTalk.
Hopefully this is now more clear
