Perko switch vs battery isolator

Howdy all. I am planning on purchasing a boat in the near future. I am trying to work out all the details before hand and am even purchasing a few of the small items.

I have a questions as to how to wire the batteries. The boat I am looking at has a 24v trolling motor system. It also has a 12v battery for starting the motor. I want to add an additional 12v battery for electronics (home battery).

The two easiest options are a Perko switch and/or a battery isolator.

These two things do almost the same thing, but not quite. The Perko allows me to choose batt 1, batt 2, neither, or both. The both is kind of what I am going for, but if I get a bad cell, it will drain both batteries. OR if I leave the radio on overnight, it will drain both my starter and house battery.
The battery isolator allows for both batteries to be charged by the alternator when the motor is running. OR by the 3 bank battery charger that is installed in the boat. It also keeps both batteries completely separate when they are not charging so that one cannot drain the other. Now, if my starter batt drains, I will have to manually swap wires to the house batt, but at least it can be done.

Now, the old batt isolators were bad because the voltage drop was up to 1v. This never allowed either batteries to fully charge and significantly reduced their lifespan. The one that I linked from Amazon is supposed to not have the parasitic voltage loss, but I dont know if thats true or not.

I guess the other reason that I do not want the Perko... If I drop anchor and fish for 5 minutes, I do not want to have to switch from 1 to 2. Then 5 minutes later, switch from 2 to 1 to move to another channel to fish.

Finally, I guess all I am asking, someone please explain why you would use which one.