OK, let me throw a different spanner into the works, so to speak.
Once iBurst (and possibly WiMax, later on) is up and running, what are the chances of Sentech getting their act together and actually fixing/improving their network, when they start to feel the heat of competition from iBurst, and all their subscribers are dumping them in favour of iBurst?
For one thing, either ways there would be more bandwidth available to the Sentech customers who do stay on. Heck, they might even reach their 4:1 ratio. Even if that's shared instead of contended, that means 32k/bits per user, i.e. 4k/bytes/s per user guaranteed!
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koffiejunkie