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.

-- 
James