I'm on CL DSL with a static IP, (Residential plan, in Mesa, East Valley).  My plan is 5Mbps up and 40Mbps down (These are theoretical max's), in speed tests I would say it averages 2.3-4.3Mbps up and between 21-34 Mbps down.  CL DSL claims 40Mbps as their max download bandwidth.  I believe Cox claims a max of 50Mbps down and 5Mbps up. 

Though I am no expert I believe the biggest difference between DSL and Cable in bandwidth behaviour is how each handles load balancing during peak use.  I have had my DSL go offline for a split second and reinitialize during extreme peak conditions, When I had cable in the past it didn't lose link status.  While this may not sound like a big deal, I work from home  through a VPN connection to a datacenter where my companies servers are co-located.  During extended backups (I have a local mirror) I have noticed that sometimes the VPN connection goes down, causing a backup failure.  Most of our other employees are on Cox and have not noticed this issue. I can't say for sure it is the DSL but suspect it. 

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James