No love for 45?
The more I think about it, XLV is a very odd suit for the final battle. If you look at all the different suits used for final battle involving IM, each suit is has its uniqueness that factors into the plot...
Mark III - the first red/gold armor with all the IM functionality
Mark VI - the first using the new reactor which allows for the wrist laser, it also has the sticky grenade instead of the missile (until they added that too in The Avengers)
Mark VII - the first with remote suit up with wristbands and super heavy duty ammo
Mark XLII - the first suit that flies apart and can be put on anybody
Mark XLV - the first with....???? F.R.I.D.A.Y.?
I'd say F.R.I.D.A.Y. was a pretty big connection to the overall plot. It was also the most organic looking suit which ties in with the "evolving bodies" theme of Ultron and Vision.