You might want to raise TCP_RecvSpace to its maximum of 64240
to make up for high latency connections. 32768 should be enough to saturate a 2 Mbps line with a round trip delay of up to 100 ms though.
Since the uplink is much slower on ADSL, raising the TCP_SendSpace wouldn't make too much sense - but doesn't hurt much either, apart from memory consumption.
BTW: Does anyone know if Genesis / Miami are able to use the window scaling option from RFC 1323?
Wikipedia: TCP tuning
