ARH still requires you to have your nose pointed at the target because the missile still need midphase updates. It's only in the final stage where the ARH missile goes autonomous, and thus the differences are only in the final stage. SARH missiles have their own special advantage over ARH missiles. To the target aircraft, the RWRs only warn that he is being illuminated for the shot, but the RWRs cannot tell where and how close the actual missile is. In contrast, with ARH, the RWR can specifically warn the target if the seeker has gone live.
Even if the other guy has fired at you, you can still try to do some evasive maneuvers while keeping the target within your radar's FOV. Thus its good to have a radar with a large field of view. In any fight anyway, you really should never lose track of your opponent no matter what.
Using SARH---you can practice this with any flight sim---requires some experience and judgement. Basically, you should keep tabs of the seconds and note that after a certain number of second (lets say 10), either the missile have hit the target or it has missed, and you should consider abandoning it and allowing yourself evasive maneuvers. SARH is also particularly deadly if fired in ripples, like after three seconds from the first shot, you fire a second.
