Based on the numbers you have given, you would fly J for a factor of 2.3 of Y. Now of course there are many permutations (Flex vs Saver etc etc), but in general I think that 2.3 is pretty good value. I think 4 or more is closer to the ‘norm’ (if there is such a thing). But in the end, it’s worth what it’s worth TO YOU, not to any of use who may have different standards and requirements.
Bear in mind that the offer won’t last forever. It comes out of P bucket (which is no longer shown in EF). It can well sell out.