If you check back a few pages there will be all the info you need.
But in short, the SH3 has a major issue with latency spikes caused by a flaw in the Intel chipset that has been talked about and documented all over the tech web. It is an old issue, but only recently came to light since ISPs started dishing out routers and modems using the Puma 6 chipset at a mass level.
Since it is an Intel chipset, only Intel can fix it, but in the USA, there have been BETA firmwares in testing which have not seen any solid success as of yet. So the issue will remain with the SH3 for the forseeable future, or until Virgin Media replace it with an SH4 using a different chipset.
The latency spikes issue will only affect people using services that rely on accurate realtime communications (such as gaming). You would experience rubber banding, lags and random ping spikes.
Some sources to read up on the issue:
http://www.fudzilla.com/news/processors/42312-intel-s-puma-6-chip-set-falls-asleep
https://us.battle.net/forums/en/wow/topic/20752441321
http://www.ispreview.co.uk/index.ph...rgin-media-superhub-3-router-latency-bug.html
As well as the huge thread on VM forums talking about it.
People including myself have written in to complain about it and been given the SH2AC as a replacement which has been authorised by the complaints department directly, because nobody in tech support at VM knows that the SH2ac works on 200Mb so will flat out refuse to send one out, even though it 100% does works, and is confirmed to work by VM administration.
As it stands, the only pro of the SH3 over the SH2 is that the SH3 supports the 300Mb package which the 2ac does not. There are no other benefits of note.