I've been using iBike products for a couple of years, starting with the iAero II. For the last year or so, I've been using an iBike Pro III. More accurately, I've used two different iBike Pro III head units with the same sensors. They replaced the first head unit because I was getting cadence surges that couldn't be fixed by moving the sensors, which they had me do several times. (A more or less constant trope of iBike's approach to customer service is to blame the positioning of the sensors if the unit is malfunctioning. They've even blamed my bike material - titanium - for problems in the past.)
The replacement head unit they sent me was working okay, until today, when I got some kind of weird "speed spike" (iBike's expression, not mine) that corrupted the entire file, so that it indicated that I rode 147 miles at an average speed of 45 mph. In reality, I rode about 66 miles at 18-19 mph. I'm trying to work through the problem right now with Aaron Timmer (who is head of technical support at iBike). So far, he has had me move the sensors again, and suggested that it's "just one" speed spike, which I could simply remove from the file after the ride. Now, he's asking me about whether it might have something to do with my wheel set, and even whether I back-pedal a lot. Complete and utter nonsense. But it's easier (though not necessarily good business practice) to blame the customer than to concede actual problems with the hardware and/or software.
The one advantage of the iBike against other power meters out there is its relatively low price. The price is lower because, unlike SRM and similar units, it doesn't measure power directly but indirectly from various factors including tilt, wind speed, wheel speed, etc. That is not to say, however, that the iBike is inexpensive. I have spent several hundred, maybe a thousand, dollars with them over the past few years, and I feel that most of that money has been wasted; at least, the value I've received is way below the price I paid. The system is, in my experience, simply too finicky and unreliable at any price. So, the bottom line is that I will not be spending any more money on iBikes, and I will be looking to upgrade to a more reliable, less finicky bike computer by a different manufacturer as soon as I can afford to. I would not recommend the iBike to anyone.