The HDD portion of my Fusion drive died and I replaced it with an SSD.
The 'pizza tool' made cutting the old adhesive easy. The new strips were clearly marked. The repair was a complete and utter success.
As long as you are careful, the repair is not difficult. Once thing to be aware of is that the old adhesive strips are attached to a black thin film on the screen. When you remove the old adhesive it's easy to accidentally pull off that film...
My kit was missing the layout description but fortunately it was available at the website.
In my iMac, late 2015, it is not necessary to remove the old HDD. Simply disconnect it and place the new SSD in the space next to the HDD. Attach it to the chassis with velcro or double stick tape and connect it.
You don't need to buy a temp sensor!