Upgrade Minnkota or go for new?

I've got a Riptide ST with copilot/autopilot. For about $700 I can upgrade it to I-pilot link w/bluetooth apparently. That would get me basically everything- I think, The speed control, spot lock, follow contours and tracks ( I have a Helix 9 with lakemaster).

But I would really like a new ulterra. Aside from the obvious auto stow/deploy, what would be different from just buying the upgrade package for my riptide ST? I've heard the turning motor speed is better and quieter on the new units, is there anything else I should know to help with my decision?

You get the best spot lock version in a tight spot on when locked and little to no wandering when you buy a brand new trolling motor. If adding Ipilot or Ipilot link, you have the gen 1 spot lock and it may vary sometime by 20-30 ft after locked in to fish a brush pile. Trolling motor wanders with the gen 1 spot lock when adding Ipilot to a trolling motor.

So spot lock will be worse with upgrade versus a new unit.

Does it effect anything else noticeably?

When Min Kota upgraded the spot lock it was only for certain 2017 trolling motors and the upgrade wasn’t included on any add ons like Ipilot or Ipilot link. You have to buy the complete trolling motor with it on from factory. Other than that everything else with Ipilot and Ipilot link “add on” works great when you buy either and add to a trolling motor. I don’t use spot lock that much to worry about it and use Ipilot for long lining jigs and cranks all the time. The one thing else you might check out is, when Ipilot is added to a min Kota power v2 trolling motor, of which I use, you have to disconnect the foot control and cannot use it ever unless you disconnect Ipilot and re enstall foot control. I don’t know about your make of trolling motor your adding to so maybe somebody else can comment on that or read up the installation for your make of trolling motor on min Kota website under installation instructions for it. I love my Ipilot and the way it works. Check and see if with a Riptide MK trolling motor can you use your foot control with Ipilot link added on to use either.