Mercury systemview trim indicator function
 

Ok, I need some help here. My boat came with stainless marines heads up trim indicators, but they have never worked right. I had the boat up at Spectre and they adjusted them and they worked for one trip out, then returned to one side refusing to move. I'm fed up with the heads up system and ready to scrap it.

This boat also has Mercurys system view and I've used the trim indicator function on the screen for my trim settings so far.

Is it safe to rely on this system for trim settings when speeds get up in the 80mph and above range?