For me it depends on how much more velocity your getting for the extra bucks and what type of bullet is being driven. For me velocity is key. I look for velocity and deep penetration in a personal protection load, and I'm not too worried about over penetration or core/jacket seperation. I need to ensure that if I fire to save myself or a loved one that my bullet it going to stike and hit a vital organ on my adversary. I need a round that's reliable in it's penetration too. You never know what you may have to shoot through to beat your attacker. In my home, if under attack I may need to shoot through walls, floorboards, windows, solid doors. Another question is what is my adversary wearing? Tough leather jacket? Heavy cotton denim? Winter or summer dress? I may get flamed here, but given the factors stated I think high velocity FMJ may be the most reliable, but what about riccoche ???
The problem is that every makers different bullets are designed to expand at various velocities depending on the material being hit, and some +P are hotter than others.
Here is an example - Remington Golden Saber 9mm 124gr +P with muzzel velocity at 1180 ft/sec. For a modern American load that's a slight bit hot. However I read somewhere that the original European standard 9mm Parabellum load of yesteryear was 124gr driven at approx 1180 ft/sec. Cor-Bon and Black Hills give you 100 ft/sec faster than standard load, running at 1250 ft/sec. They penetrate the same as standard loads, except they expand wider usually on impact.