I've carried a G26 or a G17 for years. I've never shot a 27, but I put a mag through a 23 once, and that experience was enough to turn me off from Glocks in .40. This coming from a guy who shot IDPA with a G21.
People more knowledgeable than I claim that not enough would be gained, in terms of stopping power, to justify the greater ammo cost, slower target reacquisition, and noise. I'm inclined to agree. Lots of people have been killed by the 9mm round.