Is there any evidence to suggest it could increase the service intervals?
Without conducting alot of engine testing this would be very hard to judge indeed.
I work for Gates Power Transmission who originally designed the cam drive system for these engines.
Thousands of motored and fired engine testing is conducted which is then finally proved in actual vehicle testing.
An automatic tensioner works by having an adjustable rate spring with its own damping characterisitcs and its own adjusting and working arm. These design points are quite critical.
Unfortunately if these parts are copied poorly they can lead to failure.
The automatic tensioner helps keep the tension in an operating window.
However a fixed tensioner, which this appears to be works in a completely different way. The fact that it can only be tensioned for installation. Then is left. It does look like it will take up all the tolerance of stack up etc with the adjuster. But it will not control the dynamics in the same way e.g. thermal expansion of the engine will cause the engine to grow, the automatic tensioner can take this into account, but a fixed tensioner cannot! This will cause a rise in system tension, but also the tension levels will fluctuate alot more than standard system.
Fixed tensioners tend to be used more on motorsport applications where timing intervals are alot shorter and maybe checked more often.