If those are Tannus tires you may find going up hills much easier with lighter pneumatic tires such as Schwalbe Marathons, or the new Contis. I find that heavy tires are a lot more noticeably draggy when climbing hills.
Honestly, getting that tyre was the best thing I've ever done with the Brompton. Repairing rear punctures and topping up air so often got a bit tiring, but no more. With the kind of cycling I do I don't really notice the difference to be honest. Of course I wouldn't win a race with them but I'd need magic tyres for that! Mine is medium. But for worries about getting the damn thing on I may try the harder option next time though, just out of interest.
The hills that I struggled with were short steep inclines (I'm guessing 20% at least), rather than prolonged lesser slopes. It's just the way the land lies on the family trips we do.
