I have a MKA-51(it is a 2 piece from Jones Trolling Motors) on my Ulterra now for about 4 years and have had nothing but good experiences with it.
It has a locking release that allows for the easy movement side to side and front to back.
Very easy to use.
I'm 65 yo and no problems using this slide.
Also, you can easily remove your trolling motor in about 5 sec.
I purchased an extra top plate and attached to a Terrova as a spare for when I fish Canada. Things are a bit pricey up north so this is an insurance policy in case I have problems with my Ulterra. At least the trip can be salvaged.

https://minnkotamotors.johnsonoutdoo...ttype=standard