get the 7000SXT for less restrictive and more modern valve.

Bought a 7000sxt from Ohio Pure Water last fall and it has been working well. I just followed their instructions for assembly and had a plumber/friend connect the pipes. Even though the 7000 comes with a bypass I also put in a 3-way shutoff in front of that as well.

The 5600SXT will work just fine IF the plumbing at the softener is 3/4" and the resin volume of the softener is less than 2 cu ft. It programs the same as the 7000SXT. If you choose the 5600SXT make sure you get a top basket AND opt for the Noryl bypass over the SS one regardless of what the seller tells you.

The 7000SXT is a better choice for larger diameter plumbing at the softener and larger volume softeners. It is a larger valve and will set away from the wall farther than the 5600 thereby taking more floor space.

What is the purpose of the top basket?

Keeps resin from getting out of the control valve into the plumbing.