So I'm thinking of booking YYZ-VIE next September and thought to compare prices to see if it would be actually worth it to book WT+ and try to upgrade to Club. The price comes to around $1300 for WT+ tickets RT (with the LHR-VIE legs in economy) vs. $650 for round trip economy on the same route.

It's hard to justify spending double the amount for premium economy seats just to possibly have the privilege of spending Avios on top of that to upgrade to Club...

Am I missing something here? When would it actually be reasonable to UuA? From what I understood it's supposed to one of the best ways to use Avios but it seems it's just something else to get me to dig deeper into my pockets...