It always affects the tube; that’s why you should do the CS to BB miter last. How much it changes depends on your dimpling setup.
^^^ That setup adds ~4-5deg to the bend unless you have a fixed support block, which only works on straight stays.
I usually expect to get 6mm of additional clearance with a dimple. If you push it too far, the tube will buckle.
There are two distinct topics: UDH compatibility and Transmission compatibility. If you are not planning on running Transmission, don’t worry about it. I wouldn’t even bother with the UDH compatibility.
The Paragon slider is Transmission compatible with this insert:
But only use that if you are planning on using Transmission. It is not intended to be an adjustable slider and impacts the geometry of your bike (lowers the rear axle).
I want to emphasize again: if you don’t plan on using Transmission, I wouldn’t bother with UDH. Dropouts are more expensive, it’s heavier, it makes the frame more difficult to build, and it’s ugly on a steel bike. All my opinion!