I was just asking myself a similar question. Am booked in PY in a few days for YQB-YUL-CDG. Was hoping to upgrade YUL-CDG but 870 is currently J2. Just seeing that YYZ-CDG (880) is J6...

So was thinking of doing a SDC (switch to 880) to increase my chance of upgrade. Departure from YQB and arrival at CDG are almost the same...

What would be the best approach? Call concierge on day of departure to do a SDC? Would I be put on upgrade waitlist?

Thoughts?

Thanks,

R&F