My experience with my second bub - I was 3cm dilated beforehand, they broke my water and nothing happened. Ended up on the drip.

That said, I was only given 4 hours - and three of those hours I begged, borrowed and stole. My idiot OB told me if it was going to start, it would start in an hour. When it didn't I basically disappeared, walking around the hospital for another 2 hours. If they couldn't find me they couldn't hook me up to anything lol. When I got back I begged for one more hour which I begrudgingly got. After that they weren't playing anymore

I was also earlier than 41 weeks so that probably affected my experience too..

Once my water was broken things went pear shaped very similar to what Sherie described with her birth - posterior and malpositioned baby which couldn't move without fluid...then fetal distress...it wasn't great.

Ultimately it's your decision, it sounds like you understand the risks. I would ask the OB exactly how long he is prepared to wait though. You might find his idea of reasonable and yours are very different. Most OB's are paranoid about women wandering around without their waters intact.

Good luck