Seems like a good product. Hoping it lasts a bunch of years. We had a nectar all foam. It had huge canyon's in just 3 years I think. It's tough to measure the inches because the top layer foam recovers.
The lower support layer not to much. Hoping your firm spring load model will do better. Thanks for building this product we will give it a spin over the next couple of seasons and give you a holler if it seems to ware well or not so well. Best regards, lisa