As has been mentioned sky go for absolute stability not speed.
Sky tries to get a speed which means your line will never drop out.
It'll be because the O2 speed was not totally stable.
Most people don't even notice drop outs.
You'll notice a sky line can have an uptime of half a year quite often without drop outs.
Ultimately most customers want it to work. They're happy to lose some speed if their lines totally stable and perfect.
When you say drop outs do you mean the: Uptime: 63 days, 17:06:31
I'm happy to lose speed for stability as long as its not syncing below 4000 otherwise iplayer etc don't work. Just the whole debacle of SKY CS is what makes me want to leave O2 before the full takeover.