I prefer as close to 100% weight retention as possible and a bullet that expands to 2 or 2.5 times the calibre. 40-50% loss is unacceptable(even if they were designed to do that). NP work fine on softer skin animals. Bigger tougher animals I would not use them. I much rather prefer a quality bonded expanding bullet, especially on tough African animals. I would definately not use them on Eland and up. Perfect broadside shots are not always possible, sometimes you need to take quartering or full frontal shots and that's when a quality bonded bullet comes into it's own.
Swift A frame, Trophy bonded bear claws come to mind with the best being SA made Rhino solid shank bonded expanding bullets.
I also prefer to use heavy for calibre bullets at a sensible velocity, they just work a lot better on our African game.
Speed only kills on the freeway.
I mainly use 7 x 57(170 gr Rhinos), 7 x 65R(170 gr Rhinos, 9.3 x 74R(286 and 320 gr Rhinos), 375 H&H(300 gr Accubond, 340 gr, 350 gr, 380 gr Rhinos), 338 Lapua Magnum(300 gr Accubonds and 286 gr Barnes TSX), 500 Jeff(570 gr Rhinos).
I have lately been trying the Nosler Accubonds and find them very accurate and they seem to hold together well. I use them for longer range applications and so far I am impressed.
As mentioned, to all their own, but the old style NP are not for me.