I used the SAP, on my Mk2, it is a pin that is made to put the saddle closer, but,
I used it on top of my steel extended seatpost, pointed back, ,
to give me more setback, which also took weight from my hands to my bum.

It,P riser, to my eye, has more kink bent to it than the M riser..
New this year is the H riser, they added 3cm to both sides of the hinge,
so bar will not strike the ground , when folded down. +3,-3 then.. but +6 when up.

I would look also into the Non Brompton , Trekking bar from Modolo,
their Model 'Dumbo' has worked in place of the P/M bar as its a very adjustable
setup of wings on a U shaped piece that would be held by the 1" clamp on top of the folding riser.

SJS had them, ask if they have been discontinued, or is just a stocking issue, at present.

the clamp setups that create adjustability are not weightless.