Opened mine up today and it runs as cool as a fool in a swimming pool, so something must be up inside your router after the bridge and cap. Lightning damage perhaps?
A few other people seem to have the same problem, judging by ebuyer feedback and some Safecom forum posts. I guess you're one of the lucky ones. The cap gets markedly hotter with big downloads, so there's a load effect. When I bought it I was on 1Mb BB and I thought it ran fairly cool. Heat started to show after an upgrade to 2Mb. The new £15 one still works...
