I had a similar dilemma over a Soul.
I'm a smudge unde 6' and was persuaded by Cotic that a medium with a 90mm stem was the way to go.
I went down this route (with a layback pin) and at the start I was seat as far back as it would go...
Now I'm on a 70mm stem with 685 wide bars with the saddle a little further forward to help climbing.
My discussions with Cotic re the Solaris are all short stem biased in advice (as per Kelvin's post ^^^). Speak to Cotic though, I've always found them pretty helpful and happy to give you 5 minutes to chat things through. They also answer emails pretty swiftly too.
It depends whether you want long and racy or short and chuckable (it's all their on their product pages I think).
Take yer pick...