We're using both blue and grey... with no problems.. I think it's just a load of 'bovine poo' too....... what next? "ah.. you have X router.. you need Y router!" ... suuuuure.. I wouldn't put anything past those Injun call centres...

We've had no significant speed issues of late, although, our connection here did let us down last night a couple of times - first time in AGES (we're on the 4mb connection and in Manchester)
But we're back on a ridiculously healthy 3.85Mb