They certainly didn't take over the resort, but Pop definitely took some "spill over". So to say they won't at all effect Pop I think is false. We didn't use the Food Court in the AM, so that wasn't an issue. They were at the pool late night (being a little wild...I agree just kids being kids), after my kids were in bed, (I only saw them when I was doing laundry). Since their schedules keep them very busy at WWofS during the day, they were not a problem then. The only time they impacted my vacation was leaving the parks at night. If I can be truthful, the kids were fine; it was the chaperones...and I use that term very loosely. On 2 evenings, once at MK and once at Ep, we were waiting in line for the bus back. If there were a few of their group in line ahead they'd all cut and join them. One time the cheerleader basically said, "Mom, we can't stay up here. These people have been waiting." The mom ignored her. I am not talking about 2 or 3 people popping up to their family after a bathroom break. I am talking about groups of 10 or 12 just strolling ahead of 100 people in line. It was infuriating! Not only because it wasn't a fair thing to do, but because of the example it set for every single kid witnessing it. Mind you, I was with my DH and 3 princesses, plus 6 months pregnant at the time...
Sorry for the long story. However, I thought I should share my firsthand experience. Of course that was in 2004 and a lot could change. And I should say, I loved everything about Pop and probably would change when I go versus where I stay.
Good luck deciding.