Not sure about the PD model, but the Terrova is electric steer/foot control and comes with autopilot (based on compass heading not gps), and has a constant on feature as well to maintain desired speed. You can just point the boat in the direction you want, hit the footcontrol button AP & set the speed via the speed knob, and it will maintain that compass heading & speed until you change it. Wind & current do affect it tho. I use this quite a bit and when I get a fish on, I know the boat will continue on the course I want, and will maintain the speed. You can reel in the fish w/o having to keep your foot on the foot control, just glance up and make sure you're still in a good position for fishing or not going to hit anything, etc., Your other line(s) keep fishing while you're dealing with the one hooked. You can even move the back of the boat and do whatever and come back up to the front, boat is still on the same basic course.
Check the MK website and see if you can just add the AP feature to your current TM or would need to upgrade all the way around with a new TM. I recently installed a 12v Terrova 55# 48" shaft on my Tracker PT175 and it has the AP feature with constant on so the Terrova will maintain the same heading and speed I set until I change it. I added the Ipilot as well for the spot lock and record a track, but my Ipilot is the older version with only 3 memory locations for these 2 features, the newer models have 6 memory locations. Cabelas may still have some Terrovas like I got for $550 and I paid $300 for the Ipilot, very happy with the upgrade. I did not see spending the $$ for the 3 additional memory locations for my situation.
GO BIG ORANGE !
I meant to behave, but there were just way too many other options available at the time.