It would be great. Does mean I'd drop the 1Mbps service and go back to 600 of course, as I only really have the 1Mbps for 256kbps upstream.
To me, with the upstream limits, NTL's services are much more expensive than ADSL because you need a higher package to get the same level of upstream

.
As for feasibility, there has been mention about technical limits... hmm, if you can have 256kbps on 1Mbps, then why not on 600kbps? Surely it's just a cap issue?