One advantage of the Google Play Editions of the HTC One and the Samsung Galaxy S4, is that they run stock Android. Stock Android means that the operating system is not bogged down by bloatware, and hence leaner and meaner. But that does not seem to be necessarily the case.
GSM Arena conducted benchmark tests on the HTC One Google Play Edition which show that it really does not run faster than the Sense 5 equipped HTC One. The HTC One Google Play Edition did perform better in the Pi, Linpack, Quadrant, GL 2.5 Eqypt and Sunspider benchmarks, but fell behind in Geekbench 2, AnTuTu, Epic Citadel and Vellamo benchmarks.
The Samsung Galaxy S4 Google Play Edition fared even worse. While the Samsung Galaxy S4 Google Play Edition performed better in the Pi, Linpack, AnTuTu benchmarks, it fell behind in the Geekbench 2, Quadrant, GL 2.5 Eqypt, GL 2.7 T-Rex, Epic Citadel, Sunspider and Vellamo benchmarks. The Samsung Galaxy S4 Google Play Edition actually performed disastrously in the GLBenchmark 2.5 Egypt, Sunspider and Vellamo benchmarks.
Now, benchmarks are just benchmarks, and do not always reflect real world performance. But this is something to think about before forking out big bucks for a Google Play Edition phone.
The news seems to be that the Moto X Google Play Edition will not be running vanilla Android. With the Motorola-modified software, some of the custom hardware on the Moto X will not work. And with the Motorola optimizations to the Moto X file system, its performance will not be up to snuff with the stock carrier models.
This should not blamed on HTC or Samsung. Notably, even the Google Nexus 4 is in the same boat when compared to the phone on which it was based on. The LG Optimus G, beats the Nexus 4 in half the benchmarks. Apparently, there is a lot to be said for proprietary manufacturer optimizations.