I have been messing around with it on occasion. I am not an official beta tester for Inside Ride, but I did buy the controller when it became available.

Hopefully it is acceptable to the mods to post this link rather than type a whole lot.
http://thecyclingaddiction.blogspot.com/...ss-control-beta.html

I tend to use the Kickr with power meter control first because I simply have a bike and power meter dedicated to the Kickr, whereas, I have to use my primary road bike and it takes me a little longer to setup. Therefore, I have only used it a few times. At first I had difficulty setting it up and understanding how it works. Because the bike is free to move it brings in more complications compared to a bike that is locked into place. After I understood what was going on I can now set it up quickly and get right into training. If I used it daily it would be a lot easier. It pairs in TrainerRoad just as fast as the Kickr and though it is not supposed to work this way according to one of the guys at Inside Ride, I've had the most success using power meter control.

I think they still have a few kinks to work out (Still in Beta), but I think this could be a really great indoor training using rollers with ERG. I have not tried it yet with short drastic interval jumps yet.
Disclaimer: I'm just a recreational roadie that buys and uses equipment like others. I am not a professional reviewer, but I do like to share my N=1 experiences if it can help others.

I'd be curious how much it uses the mag resistance. I typically have mine set between O and 1 to keep things spinning as fast as possible. That give me the best road feel, more mag generally makes it feel more like a trainer.

0-1 gives enough resistance for any workout I need with an FTP of 350 to 360w. I'm generally in my 11-13 and big ring.

I have to start super low just to get ERG to work. With wireless control is starts with 0 position (mag is completely off the flywheel) and keep it on my lowest gear (50 / 28). At that point when the TR workout starts to ramp up I can feel the resistance begin to change, but I must keep it down in that gear for it to work until I can get up to a certain wattage. Unlike the Kickr or other trainers where gearing does not make a difference in ERG.

My FTP is way lower than your FTP so your results would probably be different and you could potentially use a different gear than I am using at the start. Once I get more toward 200 watts I can shift up a few cogs if I don't want to spin that fast. So even though it is in ERG I still can shift and it makes a bit of a difference as to how it feels much like you described. You can tell once you gear up too much as your power will start to exceed the interval target on the graph.

I by no means have a good grasp on all the caveats at this point, but I do like how it has worked for me so far. One of the official beta testers contacted offline and reported not having as good fortune with it as I have had. He could not get the power meter control to work and if that doesn't work there will be a difference in what the rollers will report in wattage compared to the users power meter data kind of like what is going on with the Kickr.