Are these uncorrected errors excessive?

[#1]

@BaldEagle - nice picture to go with the explanation.
@Anotherone - Thanks. I wish I understood the weirdness that can happen on the analogue copper as well as I understood the digital side.
@grahamn - Good improvement in the download sync speed, but strange change to the upstream sync *and* upstream speed tests.
On the reduced sync speed - I don't know of a good reason why it should have dropped, except perhaps as a response to the increase in upstream, and perhaps as a consequence of a limitation of the Draytek (I saw this post on a BT forum, where the same Draytek was even slower on a fibre connection!). For comparison, our ADSL line (not the regular FTTC one) syncs at 13,800Kbps down, and 1,265Kbps up.
The screenshot doesn't show enough detail to understand the SNRM values being seen for upstream. Can you post the more detailed ones (I presume they come from another screen, or from a telnet session)
You also posted an old screenshot of the ADSL Spectrum Analysis - so it would be good if you could get the same for this new router - it will give us quite an insight into where the changes have occurred (both up & down).
On the reduced speedtest speed for upstream - Even with a sync of 888Kbps, you ought to get a higher speedtest result (around 0.7Mbps I guess). It'll be worth posting the information that @Anotherone asked for, but I'm at a loss - as upstream isn't controlled by profiles in the same way that Downstream is. I can't see why you'd have any lingering effects.

[#2]

BT Wholesale Speed test run - not happy reading  
The extension lead is about 4m long, but the distance from BT socket (not master) is about 3m.
Can I also check my Internet settings are correct? Image attached.
Reverting to the old draytek and I get about .76 upstream!?!  
Update: cannot find any spectrum analysis option on the new 2850vn  
Also, uplink sync speed was the same odd 888K that the 2580 had, d/s sync slightly lower again...cannot recall the exact figure now.

[#3]

Found the cuplrit re.up stream speed. 
There is a QoS service running..something about class 1, 2,3  others and UDP each with 25%! No idea what these equate to yet, but disabling it gives .75 upload again...so am on the right track now thank goodness 
WAN1 Disable 17505.16Kbps/888.89Kbps Outbound 25% 25% 25% 25% Inactive Status Setup
WAN2 Enable 100000Kbps/100000Kbps Outbound 25% 25% 25% 25% Inactive Status Setup
WAN3 Disable 100000Kbps/100000Kbps  25% 25% 25% 25% Inactive Status Setup

[#4]

Glad you've solved the Upstream mystery.
Check your Current Line speed (Login required). This will have a bearing on your DS throughput.

[#5]

Hi,
Took me a while t reply as ie9 and chrome are refusing to let me login to the forum - is it just me or is that a known issue???
Anyway, on good old ie8, I can tell you thta my current line stats/profile with plusnet is 13.7... so not too bad.

[#6]

No, bad. It should be matching the BT IP profile and has not updated.

[#7]

The line reports we're seeing are showing that your sync is very up and down still. The first attachment should show that.
The second one is a line test I've just ran now which is showing a sync of 15991 at the moment.
Your profile on our side has increased to 16000, so I'm going to leave it at that for now.

[#8]

Chris, That would be me messing around trying to sort out my upstream speed, and the router rebooting each I changed its config. including modulation changes etc hence the 8128 figures in amongst it all.
The line and router when left alone are stable.

[#9]

I hope you are using the Disconnect method, and don't forget it is better, where you can, to do multiple config changes off-line although I appreciate there will be instances where you need to see the immediate effect of something. Bear in mind you may upset DLM but at the end of the day can always ask for a reset, but you will then be stuck with whatever for 10 days.
Edit: and avoid the ADSL/ADSL2 settings otherwise it will give you lower sync and pull your profile back down and you'll have to wait for the system to update (or the DCT). Stick to ADSL2+ (G.992.5)!