In the past, I have transferred my AmEx MR points to BA miles. I mostly fly OW so this seemed a logical choice. However, BA charges a terrible co-pay (which they call fuel surcharge) up to several hundred euros for their award tickets. Therefore, I now consider transferring to SK EB instead.

I mostly redeem my miles on transatlantic business class. Therefore, I would be interested in hearing your opinion about SK J award availability on their North American routes.

Will it be difficult to find an award seat over the Atlantic on SK in J? Are certain seasons a lot more difficult than others? How flexible do I have to be?

BA, together with OW partner AA, offers relatively good availability if I can book a couple of months ahead and can be flexible a couple of days in each direction. However, AY practically has zero availability in summer. So the variation is huge.