Just spent the morning removing the decals on my Bob Jackson and thought it worth sharing the experience, you'll see why!
Method: fingernails/various scraper type instruments/white spirit (yes, white spirit - i am an ass!)
Time taken: 30mins
Result: horrible mess, some apparently permanent paint damage :-(
Back to the drawing board, time to search online for some tips (thank you londonfgss). So...
Method: Heating up area with transfer with hairdryer and simply peeling off in one go.
Time taken: 5mins
Result: pretty much perfect
The moral of the story kids? If you got the urge to remove some transfers, please get a hairdryer.