Hi, I'm having the same thoughts as you.
The big different why sacrificing your pet is so much better than an improved succubus or imp is that +5% scales with your gear. The pet will not scale at all. This changed in TBC but in vanilla pets are not scaling. Ofc when you have bad gear the pet build might seem better.
The difference between SM ruin and DM ruin is the different flexibility it offers. Either imp corruption, life tap and siphon life or master demonologist and sacrifice. The utility of the different pets and much better area damage. A big breaking point is the debuff limit. Affliction can't really use their tools.
