Good to see you joined the club astral
As for your speeds, I get a minimum of 4-5mbps peak and offpeak I get 850ish down, saying that I also got 850 down with bt total off peak, but atleast the customer support should be better
overall you should get decent speeds I would think, as for the few weeks I have been with biz, the peak speeds seem to be anything between 1-2mbps faster than bt total peak speeds, which where at times 2mbps minimum but it would generally hover around the 3-4mbps speed, but with biz its usually 4 minimum and 5-1/2mbps highest, roughly 500-600kbps peak. It has never went as low as bt total peak speeds did.
I hope it goes good for ya
p.s.
If you are only getting a few errors or none at all, after your training period, ask for interleaving to be removed from your line, as your sync speed and bras profile with go up thus you should get more throughput.
I have about 30 error seconds in 24 hours and interleaving is turned off, and I dont notice anything happening with my internet connection with those 30 missing seconds in 24 hours, I spose its a tradeoff, if you want error correction and a more stable line then have interleaving turned on is probably the way to go, if you want your fastest sync speed and a higher bras profile and dont care for the odd error that you probably wont notice anyway, then try getting interleaving turned off.
You will never sync at 8128 with interleaving turned on, 8096 is the highest you can sync at, but where your syncing at now is genereally in the area where you should be syncing with interleaving turned on. If you want 8128 then you will have to get interleaving turned off.