Running

IIRC The key thing to note on the downhills is that there are "steps" on the way down. It's a sort of gravelly/muddy path strait down the hill but every few metres there is a plank in the ground to stop all the dirt rolling downhill. Last time I ran there I got the feeling most people were descending pretty gingerly whereas I felt pretty happy bounding down there. It's definitely worth a recce though. My main worry would be carrying too much speed into the corners. (I'll have a look to see if I can find a photo that shows the surface)

I've raced XC there once or twice and used to run around Shotover quite a lot on training runs. I didn't own spikes at the time so it's hard to make a comparison but I've run those trails tens of times in Xtalons and never felt unsteady.

The other bit of advice I've heard from experienced local racers is to keep pushing over the false flat at the top of the hill. If you look at the strava link the main part of the hill runs all the way up until you get to Old Road. At that point you turn left and run parallel to old road on a sort of open grassy boggy track that runs parallel to the road... it looks flat but it isn't, and local knowledge says that that section is where the race can be won. Most people will be flagging at the top of the main section of hill so if you can get a gap on the false flat section then all you need to do is hold on on the long descent all the way to the finish.