Andrew Thomas, I am the complete opposite to you. I labour up hills (I do a lot of hillwork though, and am definitely improving) but I fly down them at a dangerous pace. I do a lot of overtaking downhill in races. The way I see it, it's free speed!
It says non navigational and that it has "shocking inclines that ALMOST have you on your hands and knees" so no climbing either, although if the ground underfoot is particularly icy or snowy, I'm guessing you'd have a bit of scrambling to do.
Is Costo-Sternal syndrome similar to costochondritis do you know? I had a touch of that a few years back. It didn't last too long and luckily, hasn't returned.