I know loads of parents of teenagers who would say 'no'.
JCO I know where you are coming from, I have a 5 year old from hell at the moment too.
But I also agree with whoever it was that said they would marry a billionaire - not having to combine kids/work/housework and everything else, and having the luxury to do what you want, when you want, would make it a whole lot easier!
In answer to your question, I would have my kids again, but no more, because I love them. To put it slightly differently, if I hadn't had my kids, I don't think my life would have been missing anything. It would just have been different. I wouldn't have known what I was missing. Whereas now, when I see my single friends jetting off on luxurious child free city breaks, I do know what I'm missing!
I am an 'older' mum too (37 when I started) and I probably would have them younger if I could start again - but then again it depends on what stage your life is at, at the time.