I tour on my M6R, and UL out of the single front T bag, but my rack is indispensable for rolling while folded, and a major reasons I prefer my Brompton over my other folders. I've rolled my bike many miles/hours through pedestrian-only malls and parks, museums, zoos, train stations, hotels, restaurants, etc, touring pannier clipped in, no less. If I sense an official type eyeing me, I'll go up to them and ask - "you allow baby strollers here, right?" That usually works, as I am no different. I even installed the X-roller for a tip-free stability.
I also like the rack for loading up on extra water (3L) at the end of the day when wild/stealth camping for a shower, dinner, b'fast and next morning's ride.
Consider an alternate carrying method to offset the weight. My B is up to ~35lbs (loaded with tools, lock, water) and I can carry it far further on top of my shoulder (5-gallon water cooler jug style) than if it were 25lbs carried like a suitcase at my side.