Can't tell you how many thousands of fish I've taken out of temp.
I see them on the graph, I catch them.
I don't see them on the graph, I move.
Down speed and temp is a good tool absolutely.
I much prefer a quality FF.
Fish Hawk, Depth Raider or Sub Troll.
They all work and it's all about personal preference.
I run a Sub troll and it does what I want it to do.
Good luck.
Glen