Sora will shift better than Dura Ace, if it's been set up 'better'. I think anything over 105 'level' is overkill for racing on a budget (I race Sora due to budget, hasn't let me down at all). But, if you're budget is ever-ending then sure, why not have the best equipment you can buy/afford? People who spend that much probably won't notice the extra money and *feel* better about their bike and it's performance. Win/Win.
I can't comment on longevity, I'm relatively new to brifters, I've only rode MTB and Track before last year.