My Spesh Tarmac came with 2013 Sora, STI shifters and 9 speed is a whole new upgrade for Sora this year. Mine shifts as expected and I'm yet to have any problems - so I'm happy with it, considering my low-budget. Although I can't say anything for Tiagra - I'm yet to ride a bike with this years Tiagra.
A well adjusted Sora will shift better than a poorly adjusted DA groupset anyway.
Somebody on here will come with the typical roadie response that 105 is and always will be the standard - which I understand, traditions don't really die out in this sport.