Ha no worries, fortunately the new one arrived on the Monday.
Does DLM not allow the connection to improve again once it's been stable for a while then? Just ordered Infinity for my new flat (£10pm plus line rental, £50 Sainsbury's gift card and should get £130 cashback via Quidco!) and intended to just use a HH5 but maybe I'll investigate some alternative options.
It does, but DLM is flaky. The more you trigger it, the less forgiving it will be over time. DLM turned on for me on a bad day about 4 days ago and put me on quite a high interleaving depth, it has yet to bring it back down - so I've raged at BT who have found a fault and booked an engineer for Wednesday, so here's hoping.
The problem is DLM is far, far too aggressive. Whilst my line did error like crazy for a few hours that stormy night, it never dropped connection once until DLM decided to take it offline and take 10Mbps off of my speed and add a crap ton of latency. And once it turns interleaving on, you cannot turn it off unless a BT engineer finds a fault, as DLM profile resets (which means turning interleaving off) can only be done at the cabinet, not remotely anymore.
The biggest benefit of separation of the two devices as I mentioned before is you can freely reboot the router all you wish without inviting the ire of the DSLAM.