I have a PT175 tracker, and it came with a proseries MG TM which does fine imo for my boat. I can troll/longline all day on it w/o issues. Real windy days I have to speed the TM up to do what I want, but not a big issue for me. Some will say get as much TM as you can afford, some won't. If you like the DF/FF you have, get a $100 handheld gps unit for marking waypoints/brushpiles/structure/trolling tracks, etc., unless you just want an all in one model. I would suggest mounting the FF you have, even if just a temporary mount to see if you will like it and how it works before spending the $$ on another, seeing how the one you have is not even installed.
GO BIG ORANGE !
I meant to behave, but there were just way too many other options available at the time.