My son ThreeD and I have used the HHSS system successfully on several occasions ranging from lows in the 48 degree range with some wind to lows in the 30 degree range with 20-25 mph wind. I did one night down to 28 or so with 20 MPH wind with the OC on top to supplement and used no tarp. The system works well within its designed limitations.
Any time I push a system there is a learning curve and this is no exception. There is a definite fiddle factor with this setup to get it right but I think that is the way any system in a hammock works. We did switch from standard space blankets to the ones that don't make so much noise and that was a great change.
We just got our sets at the sale last fall so we are still learning. We are adding Underground Quilts 20 degree UQ's to our equipment list so will see how the two stack up and strengths and weakness of both this fall.
I find I like to lounge on the porch at home in the cool evenings with this system under me and a wool blanket in the hammock.
It works great for reading and just general laying around. I feel asleep once this past March and as it cooled off I just wrapped up in the blanket I was toasty. I may add this to the hammock this winter and see how it works too.
We like the HHSS, it is what it is, a bit fiddly but works once dialed in. ThreeD was even so lucky as to get a "one of" from the sale that is camo, I will attach a photo below of our two hammocks with HHSS from two weekends ago. We had them set up without space blankets as the temp was forecasted to get down around 50 which they did and we were both warm.