As ever the actual 'worth' of the upgrade is very much dependent on how much cash you have in the bank

There is no way on earth it is realistically ever worth paying 900 Euros to upgrade from Club to First, in the benefits you actually recieve (unless you're truly huge!), however if you're not going to miss 1,800 EUR. Missing from your account the next morning, it may become more enticing.

I really rate F over J (unlike a fair few on here) but there is no way on earth I'd pay that kind of money for it...until I win the Euro millions