I have both and I prefer my Rune. There’s not much difference in (noticeable) weight,although I do have slightly better kit on the Rune,( I don’t think there’s a large weight difference in the actual builds). The Spitfire climbs a bit better- With the Spitfire you don’t feel any pedal bob although you can see the suspension moving- with the Rune you notice the suspension moving more but it doesn’t feel ‘bobish if you know what I mean if you’ve ridden a KS Link .( I think KS Link is a smashing suspension set up- as good as any I’ve tried.) But the difference is minimal and I only notice it as a comparison as I ride both.
The traction is superb on both. (NB I’m a plodder on the ups anyway) . The Rune is way better on the downs though- it just feels right, but the spitfire is still a hoot and a holler too.
So I guess my point is whatever you’ve got, enjoy them and don’t regret that you might have bought the wrong one.