Couple of things. Potentially useful tech stuff first, then my impressions of the Hybrids compared with Piston 2.1s.
First, I've got one of those android devices that doesn't like the three button controller. There's a way to get them to work.
The problem is that there are two wired headset standards, and you can get a cheap adapter to convert between them.
'International' Standard is (starting from the plug tip) Left/Right/Ground/Microphone
But 'Non International' is L/R/M/G
So wired headsets need to use either the same wiring standard as the phone/tab, or use an adapter. The button signals are carried on the mic line I believe.
A quick web search for 'CTIA OMTP adapter' should turn one up for a few dollars if you need one. Maybe someone will find the information useful.
Also, plugging my Hybrids directly into the android device socket gave recognisable but awful sound - but with the adapter in the socket and the Hybrids plugged into the adapter the sound was night-and-day different. Something to do with earthing I suspect. So if yours sound terrible and only the middle button works...
But if you get an adapter it is up to you to research whether you need one, so at your own risk. Generally if your middle button works but the other two don't you could use an adaptor to get all 3 buttons. On android I also use (free) Jays Headset Controller app to customise the buttons.
Now the review. I'm comparing Hybrids with Pistons 2.1, both tuned as well as I can with (free/ad free) Viper4AndroidFX HQ drivers. I'm not comparing them out of the box. If you aren't using V4A on android you are probably insane anyway. I do not claim to be an expert on judging sound but I know what I like. I haven't done any burn in, assuming burn in even exists, which I do not claim.
So I like the pistons for the money and have used them a lot. Overall I found more detail at low and high frequencies with Hybrids, so the bass is less boomy and a high hat sounds more like a real high hat, but I had to tweak the midrange up more on the Hybrids and they are marginally less detailed there for my ears. Overall I prefer the Hybrids on sound, their idiosyncrasies can be tuned out and they sound just a bit better to me.
Edit: Just wanted to add that the sound stage of the Hybrids is noticeably better than the Piston 2.1s as well, which is a big part of why I prefer them.
I also found them more comfortable. With Pistons i could only wear them with Comply tips, these angled, er, ear nipples mean I can use the stock tips comfortably. I also prefer the control/mic console position. With Pistons I was always hunting to feel out which was the right hand bud. The Hybrids make it obvious. So I'm satisfied they're an upgrade on 2.1s though I wish the mids were a bit richer out of the box..