I've done exactly the same and makes a huge difference.
The last bits of glue i just rubbed off with my thumb. I then gave the area's a T-Cut and you cant tell at all where the badges were. I've even asked mates.
I seriously recommend not doing this to a red car. I've debadged mine succesfully, but my brother had a red HGT and because red fades so much over time, you could clearly see where they were, it looked better to have left them.
He's now got a red Polo G40 and he's done the same, with the same faded results.
(He's actually taken off the "G40 - supercharger" badge and stuck a "Polo C" Badge over the faded bit so chavs think their Paxo's getting its arse kicked by a 1 litre!)
It seems that red really does fade, regardless of which type/ make it is, or who put it on... Heres mine after god knows how much rubbing with T-cut. You probably wouldn't notice too much on the front wings, but the boot shows it really clearly, being flat and all...