Personnally, I really don't have the time to 'modify' to the level of my players. This makes mylife much more hectic. I already work 50+ hours, spend time with my family and have 2 hours of commute time per day. Taking time to 'modify' things is not easy.
With that said, the style of modification required was 'add bad guys'. In all cases, my PC's were able to find new and different ways to be spectacularly successful. They are very good at combat, and even using multiple opponent rules, they find ways to persevere. In this case, I don't think it was the mod or myself as a 'problem', but I give credit to them as players doing well.
I based my group on the level of the final conflict, which would have been deadly had it not been for a lucky massive damage check.