Dental floss sounds like a possibility; just be very careful when getting behind the badge with anything; it wouldn't be too hard to damage the lacqeur/paintwork...
The method I used was to get a hairdryer on a low heat setting and just warm the badge and surrounding area a bit - I never let the hairdryer get any closer to the paintwork than about 6-8 inches so as not to scorch anything, and heated very gradually (in total, probaly to a lower temperature than paintwork would acheive while parked in direct sunlight on a warm day). Simply put, I was careful, extreme temperatures aren't good for bodywork finishes, and certainly quick increases in temperature in isolated areas (with wildly different temperatures adjacent).
You only need to get the badge luke-warm and it really helps move it around because the glue softens-up ever-so-slightly.
Once I'd done that, I got a peice of fishing line, and put that behind the top edge of the badge. Having pushed some thin cotton rag under the bottom edge of the badge, I just used the fishing line to lever outwards, as opposed to 'slicing' down the glue - I think that minimised the chance of me making any marks with the line. Don't use a "lever" type method with nothing under the bottom edge of the badge though, because you're equally likely to mark the lacqeur/paintwork with that!
To remove the remaining glue (there was quite a lot using the metod above); I used some diluted "sticky-stuff-remover" (available from all kinds of places, normally a paint-safe citrus based solution. Thermal Interface Material cleaner is seemingly the same stuff too) and A LOT of gentle elbow-grease.
I don't mean to fill you full of paranoia about de-badging, I've just seen it done a few different ways with different results (some nasty marks in cases), and I just like to a) consider as much as possible, and b) play "slow and steady wins the race".
I can only really vouch for my possibly over-careful method from experience, but I can safely say I removed the badges from a black A3 that had been there for about seven years without a single mark /ubbthreads/images/graemlins/grin.gif
Hope that helps,
Rob.
