A locksmith who can't handle a multi point lock and a Eurocylinder is not really good.
The Eurocylinder lock is the best lock solution in the market and it works a breeze just like multi point locks which are by the way an ideal solution for timber as well.
And what is now wrong with double glazing of IV68 or uPVC "plastic" windows??
Of course it is better to install heaters and huge air conditioners because that has been done 20 years ago and why change now.