Much better is the construction of the older model Techamphibian 3. The current one is heavier with a worse fit and does not secure firmly on the foot

They are perfect, but the wrong size. Their fit is very narrow, you need at least one size up if you have even a regular width foot. The length is fine.

I had the first pair that Salomon released in 2000. Salomon quality. After 24 years of summer use in rivers, etc., their sole came off and I decided to get the Techamphibius 5. They show similar quality, comfortable on the foot, and with a good grip on their sole. Their durability will be proven over time.

I have bought the techamphibian from 2008 (it is still intact) 3 years ago, the techamphibian 3 (it refuses to break) and now the techamphibian 5. I use them for simple summer hikes and river crossings.
Comparatively and in terms of appearance, although I haven't tested the 5 in a river yet, I would say that the 3 was the best out of all.
Now, let's talk about the sizes... They are a bit strange if you have narrow feet.
I got the techamphibian 1 in size 44 or 44 2/3, which is the same size I wear for sports shoes. It fit perfectly in the toes, but the fit around the foot was not good because it doesn't have cushions, and it would loosen no matter how tight I tied it.
I got the techamphibian 3 (similar design to the 1) in size 43 1/2. It fits well around the foot, but the toes touch the front. I wanted to wear neoprene socks for canyoning, and it was very uncomfortable in the front (which is understandable)...
The techamphibian 5 has a different sole, and its design is narrower. I got it in size 45 1/3 on sale (unfortunately, I couldn't try the 44 2/3), but due to the narrower design, I can wear it relatively comfortably even without socks. I believe that if it had a size 44 2/3, it would be ideal for my foot.