What's your preference? I know that upsweep opens out the elbows, which. . . er. . . makes for a kinda of Tai Chi / qiqong energy harmonisation. . . or perhaps it just knackers the wrists. It seems to me that my wrists grumble more when riding bars that have more than a degree or so of upsweep.
Level perhaps the sweep angle is what is bothering you ?
no parts expendature, just loosen the death grip, and lay your hands on the grips at a different angle..
on My Brompton ... M bar + I added Ergon grips with integrated bar ends ,
the ones designated for Grip shifters are shorter. a good length , there.
Fit right on the newer type M bars . the GR2 model , shorter end,
will let the bar fold down and catch.
the larger more comfortable GC3 will require you loosen the pinch bolt,
and turn the end upright, then the handle bar will fold down and catch.
Left in the riding position it will still fold down, But miss the catch by about an inch.
toe strap will secure it there..
On My Bike Friday Pocket Llama I use ITM Trekking bars..
Perhaps you need more hand grip options,
rotating of your wrists and hands to increase the variety..
Still more mattresses needed between you and that Pea?