Thank you for the question and the replies. All very helpful. I am flying JFK MAD NCE. All flights are operated by IB. I am in economy class (XFF) with an Avios ticket booked directly with IB. My carry on is 56 x 36 x 23 compared to IB's 56 x 40 x 25 requirement but unfortunately the wheels and bumpers make my carry on longer than 56 so it will not fit in the sizer.

Does anyone have any recent experience with IB indicating they are getting more strict with checks?

When flights are full, do they only check the size or do they also check the weight at the gate? I plan to be under 10kg.