Ping times can vary a lot, depending on the packet size (usually 512 bits or 64 bytes), the DSL synch speed, and the number of hops.
ADSL is slower upstream, so a 384Kbps working at 64Kbps upstream, would take 8ms just to upload the 512 bit packet, and ping time is for the total round trip.
If in doubt run tracert, and choose a proxy with a low number of hops. I find that international speeds suck either way...
My 4Mbps line gives the following times from Cape Town to Joburg:
1 1 ms 1 ms 1 ms 192.168.1.254
2 7 ms 7 ms 8 ms 41.245.128.1
3 28 ms 29 ms 29 ms 196.43.23.214
4 28 ms 28 ms 28 ms 196.43.9.21
From my home in Cape Town to the Cape Town proxy is much faster:
1 1 ms 1 ms 1 ms 192.168.1.254
2 7 ms 8 ms 8 ms 41.245.128.1
3 8 ms 8 ms 8 ms 196.43.23.114
4 8 ms 9 ms 8 ms 196.25.255.3
192.168.1.254 is your ADSL modem, not SAIX...
DNS can change the IP of a proxy, but takes some time to propagate.