Definately worth £300 or so in my opinion.
I bought my Ed30 for £23000ish, had it for about 20 months in IMMACULATE condition with only 9000 on the clock - and some w@nkstain ran into the back of me. Insurance company are only willing to pay back 'market value' which was £16325 - which I eventually got upped to £16855.
If I had GAP, they'd have given me a cheque for the difference straight away - instead of me fighting with the insurance company for the last 8 months!
GAP is a must for me this time!