you'll find that ISPs are unhappy about ordinary domestic customers running web servers on the connection, and you'll find yourself smartly disconnected if you exceed their arbitrary bandwidth limits. There'll be no warning either, and you'll probably find something about it in your terms and conditions of service - I haven't checked.
Cable providers usually run a contention ratio of 20:1 whereas the BT ADSL service runs on 50:1. This, plus the differences in the cable system mean that cable customers generally see a slight (not much) downstream speed advantage of their ADSL neighbours. You'll rapidly be identified as a big bandwidth consumer if you're running busy websites on a home server, but to be honest why would you want to do that? You can't compete with the standard of service provided by professional hosts, you're likely to be especially vulnerable to external attacks (unless you're running expensive hardware firewalls) and I'm stuck to come up with a single advantage - apart from the fun of having a go.