There are not many unknowns on Jetstar economy - it is just an economy product , not much different to any other economy product

There isn't much point rationalising a purchase of Jetstar's business class ( which is really a premium economy product ) against the price of a product that you wouldn't have purchased or against the economy fare on Qantas if it would have been a no brainder to go on Jetstar

If you are happy paying triple the price for premium economy, then it is a good purchase