I'm flying UA LAX>LHR tomorrow. I've always just checked a single bag and carried a small backpack on. This is a longer trip with my wife, though, so I'm debating carrying a duffel bag on. It's an Adidas Gym bag (
). Stated dimensions are slightly bigger than reality. It's soft-side / smashable, and would not be even close to stuffed. Am I likely to get shut down trying to carry that on? I feel like I've seen people carry on way bigger items, but that may have been before they started cracking down. 2nd bag is a ludicrous $200, so that's not even an option.
Edit: as a data point, no issues with that bag as a carry on