Ian, I am still to purchase my first ever Flight Guide but i know what you mean. I believe the amendment service keeps everything up to date (the more expensive version) through out the year so by the end of the year 2003 you will have most or all the updates that would be in the 2004 version (correct me if I am wrong someone). But than you wont be receiving any more updates for 2004.
I believe by publishing a new flight guide every year they make sure everyone has the most recent information i.e. those that dont have the amendment service will also have to buy a new one. I think it is worth spending that little money at the beginning of the year and being sure that you have the most up-to-date flight guide for the rest of the year
