Unfortunately, I do not own an iOS device and from my understanding, you have to have a developer account just to be able to test apps on your device, even if you have no intention of ever publishing something on the store. Correct me if Im wrong on that, but everything I have seen is that the only way to test apps without a developer account is to have a jailbroken device.
I have been building an audiobook player on and off for a while now and tested it on a Galaxy Nexus, Nexus 4, and Nexus 5 in addition to my Moto X. None of those ever experienced any noticeable delays in playback. That is why I was wondering if it is a per device issue. Or it could be that I have just always used vanilla (or extremely close to it) Google Android devices. I understand that the devices I have tested with are most likely in a very low percentage of active devices used aside from the Moto X. I was basically just wanting to jump in to provide my notes on the issue, the device I tested with, and my experience.