I found almost all of the timed explosives to be difficult to use and very situational. I only really used them, and only really tin grenades, in service of Crackerjack Timing as part of my 100% achievement run (which I documented here).
Most of the time enemies don't really have strong AI enough to plan where they're going to be in 15 seconds. (Well, besides the ones that will just run up in your face...) so setting an explosive and having exactly 15 seconds to bring someone into their radius is kind of hard to do. If someone is standing still or pathing in a consistent pattern, you might be able to measure out 15 seconds and catch them in the blast, but by that point you might as well just shoot them in the face (not the hands, not the legs, etc) and get it over with.
The one situation where it could be interesting is stealth reverse-pickpocketing a live bomb into an enemy's inventory. This will cause them to become a walking time bomb, and if they're pathing into an area with other hostiles, you might be able to take them all out at once.