Well I transferred all the parts properly, but the front camera wasn’t working. Reseating it fixed the camera but then when I closed the screen it cracked. I backed out to the old screen which is held together by tape, but miraculously everything including the camera and Touch ID is fine. Better luck next time.
I enabled assistive touch before making a go on this part. Screws are very small, easy to strip, and difficult to find if they go flying when you;re just trying to seat them properly.
You don’t need a new phone, but your selfie camera and phone speaker will not work. You can get replacements for that about $10.
It was a lot easier for me to use a fingernail to remove these cables. It provides a lot less force, and is more likely to remove the cables without damaging them as they are very easy to break.
I just completed this replacement yesterday. I broke the old speaker off the ribbon cable, and lost one of the smallest screws, but my iPhone is now working ok again, and the power button works properly. The new cable and switch is definitely after market at $2 shipped, but I'm sure it will work fine. I had to fabricate a screwdriver small enough to remove the 5 point screws, and it took nearly 2 hours to finish the job, but thanks to iFixit all is well. Cheers.