I've got a 4Mbps line, on a 512 kbps package. It's supposed to be burstable from 512 - 1024 kbps, so you have to have at least a 1Mbps line to take advantage of it. And Telkom installs 384, 512 and 4096 kbps lines, with nothing in between, so there's not much of a choice there.
I have before gotten speeds of 200-300 kB/s (and on occasion 400, though rarely) on local transfers. On international I get at most 40 kB/s on HTTP if I run enough threads, and my torrent speeds fluctuate between 3 and 10 kB/s most of the time. So the only times you will get high speeds is if you have a local source to get stuff from. As I understand it, they have 98% international usage, so in theory the 4Mbps users shouldn't affect that part of the pipe at all. It does degrade the IPC link, however.
And I agree, if i decide to stay with DC, it will be on a 256 kbps package. The 512 is not delivering any more value for the money for me. And I would be happy if they throttle me down to the package speed.
And if you hear about someone getting 200 kB/s, check his destination. It's almost guaranteed to be local.