I haven't upgraded to 1.09 yet, but in the previous version I used these rockets for AG missions, being "very" effective against buildings. You cant see the explosions, but when u hit a small building, the building is destroyed.
I cant understand the timed OR impact system, but not both. It is clear that when the rocket impacts something, the timer will be of litte usage. The logical way having both systems available would be to activate a timer, but explode upon impact if its the case.