I can’t comment on the Spitfire but I’m really happy with my Rune.
I’ve had it since June and it climbs better than that sortbof bike should and is great at descending although due to it being pretty slack and long it can be a handful in tight switchbacks. The KS suspension works really well with the CCDBa (i demo’d it with the Fox CTD shock and didn’t really like it) the only downside is that it dies collect a bit of mud and can be a pain to clean.
The quality of my frame was really high and it came with a load of zip ties, post, seat clamp, stickers, volume reducer spacers and spare seals for the shock as well as the flip chips to change the geometry. Keith the designer was really helpful when I emailed him too.
The other thing that I really like is that they’re quite rare. I’ve not seen another one on the trails yet.
I’d say do it…I really like them. If I’m honest the Spitfire is the bike that I probably should have bought but I wanted to demo before buying and couldn’t but was able to demo the Rune and I loved it.