Do not assume that because 27's are SAR they are inferior. If I fly a mig I use 2 ERs and 2 77s. They have longer range for a start, and make HOJ shots very powerful at altitude. Also, myself I find it easier to dodge an active missle because of the RWR countdown (in ru jets) than a SAR which gives you no indication of proximity.
Of course, there are situations where active missiles are better too, and since 1.11 they have been somewhat nerfed as it is much easier to break locks by beaming.