Appart from the angle its positioned at, is there a difference in positioning between top swing and conventional front mech cable guide mounts?

After trashing too many top swing mechs’s I went back to a conventional one (a ridiculously old 8s LX one), but the shifting has never been perfect.

Is it
a) the positioning makes the cable pull slightly different?
b) its an 8s mech and isn’t working well on 9s chain and rings?

And why did the designer in his infinite wisdom choose to make a hardtail specificly for the UK that only takes a mud clogging top swing mech!!!!!!! Had to take a file to his handywork to remove the lower bottle boss and fit the conventional mech.