There people on both sides, there are people who say Icecaps are noisy and those who say they are quiet and vise versa with the gyre.
I think with both part of it is expectations. I also think both are quiet compared to my mp40's.
I had one gyre that got loud but I had messed up a part. The gyre are not the easiest to take apart and put back together and I sometimes think people wreck a part or put them together wrong.
I have had gyres since launch and I had never a issue except the one which was my fault.
Also as far as reviews go people that have issues or think they have issues are far more vocal than those who do not.
My cousin just asked me about the Icecaps because he heard they were noisy because of a few reviews. I told him that I do not trust reviews and usually problems are blown out of proportion. He bought the Icecap version and it was quite. If you are getting air in them they are too close to the surface and of coarse that will make them louder or you need to make sure no air is with them if putting them in the water.
I can find out who makes the IceCap brand of gyres.. IceCap brand I beleive is now owned by Coralvue.. I beleive allot of Icecap is rebranded and some products Coralvue hires someone to manufacture.