I'm on an 8mb ADSL connection that's had zero downtime in the last two years. That said, my ISP only provide an 8mb service so downgrading isn't an option unless I move ISP.
I'm paying over the odds for the service (£25/month) but I do get 11 POP3 mailboxes, plus 2GB of webspace and 20GB monthly downloads (I currently don't even use 3GB/month).
There were apparently a load of problems after upgrading exchanges to ADSLMax, but I've experienced none of this. The only problem I've had turned out to be a BT line fault.
on a dsl connection the amount of people on the same exchange is not suppose to matter.
afaik Orange do not supply a DSL service - its ADSL, so you'd need to look into their contention ratio before signing up. My ISP is 50:1 but as I said before, never had any problems at all.