[BTirish]

Well, the fold might be correct as you may be drawing dead. However, like you said, your information raise on 5th saves you only one bet if in fact you are dead, where if there's any doubt that he has quads you can call down for $300 and hopefully fill up. If you can think of no likely hand other than quads for the villain to have 4-bet with on 4th, then just fold on 5th and save the $200.

So, I'd say the play is either to call down or to fold on 5th, and I know I'd always lean towards calling down unless this opponent is really that tight-weak-passive. The reason I think there's more value in paying $300 to potentially win the pot than in the raise-fold line is that I don't think the information raise is "informative" enough on 5th street--he may have just filled up. You don't have a pair on board so he would always be ahead with a full house.