Sounds like you're onto a plan artechim ;-)

Afm my girl pg have been more 'difficult' but not remarkably so... Or is that just the rose coloured glasses of hindsight LOL.
For me I doubt age has (had much chance) to play a part as I had my 1st at 20 and my 5th a couple months off 27. I am finding all the other answers really interesting. I'll have to ask mil her opinion as she had her 1st at 19 and last at 44.