HELflyer

If your trip includes codeshares on non-BA metal, does it just mean you sit in the class you paid for on the non-BA leg (but they still take the miles(?)) or that you can't MFU at all if your trip is not all BA metal?

For me that could be a problem, as most flights HEL-LHR are AY operated - I think there's just one BA operated flight daily, which doesn't connect that nicely with most onward flights. Even if the LHR lounges are nice, well... I'm not looking toward spending several hours in them.

Actually, on that particular route, it seems HEL-LHR-SYD can be several hundred € cheaper than LHR-SYD if booked in J, but not so in WT+ (HEL-LHR added 450€ to the price on one random date I checked). I suspect the J difference may be in part due to taxes, but perhaps more a marketing decision to bring the J fare on par with direct AY/QF flights from HEL. For WT+ they wouldn't need to do the same, as the HEL-SIN (or BKK) segment is on AY metal which only has Y and J cabins, so it's not an option for people looking for a price and product between those.

This about SYD isn't purely hypothetical, we might be planning a trip there some day - and while I'm not saying 50K miles per person for MFU (or 62,5K ex-HEL) wouldn't be a good value, the problem would be collecting the required 115K for two by the time we'd be booking the tickets, so we might not have enough for all segments (assuming we can even find availability on all).

Upgrading one way only is of course one option for less miles, as is making the onward leg from SIN/BKK/? a separate booking. But at least it seems we'd be better off booking the long-hauls ex-LHR to bring the miles requirement down to 100K from 115K - would even save some money if including HEL-LHR indeed costs 450€ more, as there's no shortage of options for HEL-LON at that price...