I used to know a couple of traders in he US who used cable primary and dsl backup, which would suggest they had more faith in the cable either for stability or speed. Not suggesting you need to have both but rather pointing out their order of preference. BTW your cable download speed looks wrong, 3.0kbs would be a slow dialup.
Once you go above a modest speed stability should be yur primary concern as far as the trading is concerned. 0.5Mbs is plenty fast enough to trade. Upstream speed is of little importance as the amount of data you send in trading is minimal