Rhino Liner
I've heard, EXACTLY, the same thing you just heard. You are, also, in a hot area of the country and I would think the problem would be more pronounced than if you lived in an area without as much sunlight.
I have nothing against Rhino but, I have heard that the product is not as durable as some of the others, such as Line-X. The story I was told was that there are 2 different methods for installing these liners. The HOT method & the COLD method. The hot method dries almost instantaneously while the cold dries at a slower rate. Some of the differences are that with the cold, you have to "pile-on" more material on the ribs going down the floor of the bed because, the cold, since it doesn't dry quickly, wants to slump down into the valleys, from the peaks of the ribs. Also, the material has a tendency to run and drip off the sides and side rails, of the bed. A good installer can probably avoid those problems but, you never know what your going to get. Another thing I heard was that the texture ends up looking more like "cottage cheese", rather than a finer texture.
The hot technique dries before it can slump into the valleys and sticks to the sides and side rails better.
I got a product (hot) similar to Line-X, locally, and I'm very happy with the quality of the installation and the durability, so far. I was able to get mine at a show price ($300. 00) just by asking if they were going to have a sale, in the near future. The owner gave me the sale coupon and told me that whenever I was ready, present the coupon.
I would, also, highly recommend getting the product installed over the top, side rails and the top edge of the tailgate. Just for the extra protection.
I, in no way, mean to critisize anyone's product, here. It just pays to do your homework and then make a decision as to what will work best, for you.
Hope this helps.
Joe F. (Buffalo)