It would really helpful if some owners took measurements before and after to quantitatively measure how effective they are. There are all sorts of apps for smart phones that could be used.
Just got mine installed today. They arrived at about 07:45 and drove out at 17:00. They are robust enough that slings will not be even a slight consideration.
Prior to doing this, I attempted to quantitively measure roll and roll accelerations using an artificial horizon app on my iPhone. The app works very well and reliably, however the data was really a failure. It is difficult to find consistent conditions (I went looking for Washington State ferry wakes as a standard reference), that could be reliably duplicated post install, but it is nearly impossible. Second, even in some short periods of nasty rolling, the data show very modest angles though fairly quick accelerations. 10 deg each side will send stuff across counter tops. Contrast to my sailboat where 10 degrees is just starting to get a decent sailing breeze. This leads me to believe it is the roll accelerations and rates, rather than the angles, that are unpleasant. The sailboat roll rate and accelerations are much slower. I also attempted to rock the boat in the berth by various means, again this really yields disappointing figures when actually measured.
I did take detailed speed and consumption data which I will compare to post install.
I had intended to return the boat to the water immediately to get as fresh a comparison as possible, but plans have changed and it won't be back in for several weeks. I think the best way to get a comparison is to cruise side-by-side with a sistership and either measure or observe the result. I intend to try and orchestrate this in the short term.
I note that in the many threads on rolling chocks, there are skeptics who don't have them, and believers who do. There does not appear to be an alumni of people who have them and say they don't work. This could be the placebo effect of having spent good money and not wanting to admit error, but is seems to be pretty universal. I made my own decision after talking at some depth with the owner of a sistership who had several years of experience and many miles on the boat both before and after the install. "No brainer" he called it.
Second note is that "rolling chocks" covers a lot of ground, from little dainty short things on big boats, to big wings on little boats. These two cannot have the same effect, so one must be specific in descriptions. Mine were installed by Roy Brown who has done quite a lot of them (300+ he said), has changed them through the years based on experience, and they are relatively large.
