New Mountainbike

Anything which moves can be prone to failure ...

Personally, between the two, I would opt for the SCOTT Scale 940 bike with the aluminum frame ...

Unless you are keen on the color scheme of the Scale 930, I would leave the carbon fiber MTB framesets to the competitive riders

AND, especially, I would choose the Scale 940 because it has Shimano SLX components instead of SRAM components (from MY observation, SRAM North America has a very bad business model & consequently terrible customer service/relations, IMO ... especially, when compared to Shimano's North American excellent customer service ... ).

FWIW. I have been on some fairly steep hiking trails ...

While I am not convinced that 27er are truly viable as an alternative, yet, depending on YOUR height & the inclines which you expect to encounter, you may not want to consider a 29er ... by MY reckoning, I am at the short end of an acceptable height for a 29er (5'9" / 175cm).

Choose the frame size based on the virtual top tube length ... in the past, magazine reviewers would compare a MEDIUM 29er against a MEDIUM 26er!!!

• by my reckoning, a SMALL 29er is equivalent to a MEDIUM 26er, etc.
  
• so, I reckon that 'I' would opt for a SMALL 29er
  

Thanks al lot for that really competent answer!