I actually work for a cable company
(SPOILER)(charter) and we get the higher tier ( I believe its 20 MB now?) for nothing. we are soon going to be updating our QAM and start "Narrowbanding" to each nodes to give more bandwidth and speed so I am actually hopefully looking at 50 MB for nothing soon. Plus My service is great! My connection never drops off and I havent had an outage yet. plus if I ever do have a problem, its nothing I can't handle on my own or call in a system tech to check on for me for free.
and the only problem with DSL over cable is the shared bandwidth but I live way WAY out in the country and I am actually on the last port of the cable plant so my speed is always topped out any time of the day.