I would NEVER put 5 people in a studio at Poly and not in any other studio for that matter.
We stayed 3 in a poly studio and it was SMALL and cramped. Had we traveled 5 and stayed in Poly my best guess (knowing my family) it would have had a negative impact on our vacation.
Staying 5 should for the best comfort should be a 2br, but a 1br might do in some cases but that entirely depends on the guests staying. My girls are 6,12,12 and there is no way they would stay in a 1BR sleeping in the living room. My 6yo would do fine sleeping in the master with her mother and I. All families are different and when we go on vacation I rather have too much space than too little. I'm not ready to risk the vacation just because I didn't book the right size accommodation.
Other families might be fine in a studio or 1br staying 5 people.
With all that said, we have stayed in both VGF and PVB and we like the VGF the most. Both are great but the theming at VGF is just more to our liking than PVB.