Is there a problem with PlusNet's default DNS addresses?

[#1]

Since Christmas, I've been suffering from very slow page loading on all web sites - especially in the evening or during PlusNet's peak times. At first I just thought it was down to contention in the evenings, as my router still reports it's connected at 7904 kbps Upstream (and  448 kbps Downstream). I tried a number of things, including rebooting the router, updating the firmware, turning off wireless and using Ethernet etc, etc, but the results were the same. However, Off-peak times were a bit faster, though not as fast as they should be for an 8Mb line.
My router (a NetGear DG834GT) has always been set to get the DNS dynamically from the ISP, in this case PlusNet, which has been fine for ages - it's only really become unbearably slow in the last two or three weeks.
Anyway, to cut a rather long, and boring, story short, I read about the OpenDNS service on another forum so thought I'd give it a try. So I deselected the option to dynamically get the DNS from PlusNet and I inputted the OpenDNS addresses into my router...
Primary: 208.67.222.222
Secondary: 208.67.220.220
...then hit the Apply button, and the difference was like night and day...instantly noticably fast.
My broadband is now a joy to use again!! Whereas before, I was waiting an average up to 30 seconds (sometime longer) for simple pages to load, now it's almost instant. Basically, it's now like Broadband should be. My sanity is now restored, as I was sure something was wrong with either my equipment or the telephone line - I now know that there's nothing wrong at my side, it's PlusNet that are causing the slowdown.
So, my question is this...
Is there a problem with PlusNet's DNS addresses - the ones that it allocates dynamically to your router? And if so, are they aware of the issue, and working on a fix? Also, is it safe to use a service such as OpenDNS - is there anything I need to be aware of?
Cheers,
Steve

[#2]

I've found the same thing and have switched to OpenDNS, certainly made ebay and facebook a bit snappier.

[#3]

It's more likely to be down to the DNS proxy in your router than PN's servers.
If you manually assign DNS severs in the router it hands these directly to the PC via DHCP.  If you don't specify DNS addresses the router will hand out its own IP as the DNS server and will proxy DNS requests.  (You can verify this by opening a command prompt and typing ipconfig/all and looking at the assigned DNS servers.)
Basically your PC is now being assigned OpenDNS's servers and querying them directly rather than querying your router which would then query PN's servers and hand the result back to your PC.
You could try entering PN's servers manually into your router to see if it makes a difference!!  Manualy entering the DNS servers into the TCP/IP settings on your PC will have the same effect.