I wish I could remember all the details but I did read that someone asked customers over several years their experiences with Shimano Alivio and Deore (probably equivalent to Sora and Tiagra). Deore apparently runs smoother when pedaling fast and does not need to be adjusted as often as Alivio. And the long distance cyclists on this site insist Deore LX (probably 105 equivalent) will last longer than Deore.

That being said, I don't doubt Salsa sells good bicycles but my own personal choice might be a bike like the Trek CrossRip with the Shimano Claris groupset and buy 8-speed Shimano Ultegra bar-end shifters from Chainreactioncycles.