I have had 2 OP births and I never felt them in my back like you are 'supposed' to. They weren't alot different to my first two births really. THe only thing with my last one that I found hard was that he turned right at the last minute as he was crowning which made it very hard to push him out. Those births were only 4.5 and 6 hours long - so very hard and very intense but nothing I'd say I'd hate to do again.