I've dented a smaller lipo and as long as its not "accordioned" with a number or so really small, sharp folds, I think you're fine. Denting one really bad you'll see some loss cause that area doesn't seem to contribute to the amp flow anymore. I got pretty much normal life out of my dented one compared to others. I did same thing you're doing - more protection.

About a week later was running around climbing a debris pile (construction site) and managed to puncture one - I was lucky, I was standing right there and ripped shell off and tossed batt soon as I saw smoke. Would have melted chassis otherwise. Also got me a visit from site security guard due to all the smoke. Fortunately he had a sense of humor and we had a good laugh.