It's hard to predict what sort of increase you would see without any stats, such as:
Data rate
Maximum data rate
Noise margin
Line attenuation
Signal attenuation
which are all available in Troubleshooting/Helpdesk on the web GUI,

but you should see an improvement in your speed.

Data rate: 6836 / 28682
Maximum data rate: 6839 / 32001
Noise margin: 5.8 / 7.1
Line attenuation: 30.9 / 28.1
Signal attenuation: 30.8 / 24.8

That speed looks pretty good for that attenuation to be honest, although I note your noise margin is above the target of 6 so you should see a few Mbps improvement with a HG612 modem. It's not going to double though...

In reply to a post by Storm_Force:

Apology for hijacking this thread just a quick question.
I am served by a Huawei cab and use the home hub 5, would I benefit by changing to the HG612 eg would I see a speed increase (currently on 30mb)

I presume you mean using the HG612 as a modem and use the HH5 as the router/wifi.

I did the same (have a HH5A) and with the HG612 got about 10% better upload speed. Download speed the same. You can find them pretty cheap on eBay.

Thanks to all, I just bought the Draytek one in the end. Just easier and you can play with / see the stats which I haven't been able to before.

The Draytek is a very good modem and about to be one of the few (so far) 3rd party units to get BT SIN 498 - MCT Approval for VDSL2

http://www.draytek.co.uk/information/our-technology/...

Another (minor) thread hijack here - is there an official supply route for new HG612 modems?
I'm probably going to need a few for an upcoming project but don't really want to push "ebayed" stuff on to a customer's site...

I've only ever seen them 2nd hand on Ebay, apart from Openreach providing them as part of a managed install.

If you want new, you're probably looking at a Billion 8800NL or Zyxel VMG8324 instead.

How many is a few?

Initially 3 or 4 - we've used them with our preferred firewall appliances before and they work well.
I'm a big fan of the Billion 8800NL but it's almost too good a router to use solely as a modem. The Vigor 130 is the other option I've considered and I think it's the one I'm leaning towards now the HG612 is going for silly second hand prices...

Have you considered the TP Link W9970 VDSL2 modem/router the wireless may only be 802.11n but there is G.INP, vectoring and a bridge mode and believed to be a Broadcom chipset at just £33.33 each currently and three year warranty. Also can do 3g/4g failover with dongle and option to re-assign 1 LAN port as an Ethernet WAN port.

Have been using the device in router mode so far (22 hours), and want to leave it a few days like that before fiddling with bridge mode. My VDSL2 is not fast and while same speeds as other kit so far, the noise margins are a little more stable at night so might see the margin drop another 3dB to get me above 20 Mbps soon.