In my experience it's a fantastic opener with an insane amount of versatility in terms of when and how it transitions. And additionally, it leads to some serious sleeper compositions like Adept Chargelot (Adepts shading on top of the bio or Battle Mech to prevent kiting while Chargelots close the distance).
And to further this, you're not so gas starved you can't open with a chrono'd Stalker to handle the scouting Reaper, nor are you so gas starved you can't get a fast +1 armor or an additional 2 Stalkers to catch HeroMarine's 3 mine drop opener as it jets into your base...
It just blows my mind that such a potent opener that transitions so well is basically not used. Especially since it handles cheese fairly well too, going as far as being able to hard counter Maru's proxy marauder concussive shell blindly with a partial probe pull.
Any ideas as to why it's not used? Especially by pros in PvT?
Edit; because it would really help if I provided replays...here are a few!
Now imagine if a pro did something based on this opener instead of a D2 baddie.