Building a home from scratch, you would do the loop. When we remodeled, the pump was like $300 installed versus running the new loop line under slab, through walls, etc.

The valve doesn't dump water down the drain, it recirculates it through the recirc line.

Dumping it would waste water and energy, and is likely not allowed.

It's hard to say exacty how tough it would be to run the line. If you have a plumbing stack to follow, you might only need to cut a couple of holes in the walls in a couple of places to drill a new hole through the sill plates/heads. You can fish a 1/4" or 3/8" copper line through a stud cavity pretty easily.

We installed it at my house, works great, no loop required.

The original pump linked, the Watts 500800, says installation simply requires installing in the pump in the line and sensor by the furthest fixture.

I wholeheartedly recommend it. During the dead of winter it is AMAZING to have immediate hot water.

even existed.