I own both the 27 and the 29. The 29 is larger but still concealable in winter time. In the summer the 27 (in my opinion) is the way to go. The 29 magazine holds 10 rounds.
A recoil comparison of full power defense 40s in the 27 and full power defense 10mm in the 29 is pretty close. Some 10mm loads which are still considered safe and below the maximum are (in my opinion) a handful in the 29. I load a 185 grain bullet going about 1150fps in the 29 and it's about the max I would want to fire on a regular basis. Yet it's still 50-100 fps below the max published velocity. Factory Hornady XTP 155 gr rated at 1265 fps are a nice defense load for the G29
You really can't (or at least shouldn't) load the 40 that hot that it becomes a problem in the 27, like some of the hotter 10mm can be in the 29.