The general consensus agrees with you---that it is a "downside" to have bigger jumps between cogs than smaller jumps, and likewise, that more cogs are better. I have never agreed with this consensus for two reasons. If you are in a little harder to pedal gear than you want, just take it as an opportunity to HTFU and pedal harder. And number two, with fewer cogs, you waste less time double shifting and waste less time shifting altogether.

I have two old race bikes I keep in other States with eight speed drive trains. I never feel cheated at all when I go back and ride those old bikes as a result of the fewer cogs and wider spacing. I still love training on them. And the prospect of the coming 11 speed cassettes just makes me yawn.

OP, just get the Ultegra 12-27 and don't give the slightly wider spacing a second thought. JMO.