I am of the opinion that the only thing the plastic tip bullets do is feed better from some mags then hollow points, in rarer cases soft points do.
I'm not an expert, and what I'm saying is more of an educated guess, but I know enough to be fairly certain about the following.
No matter what is on the tip of a bullet, the performance on game is determained by the jacket construction, and its interaction with the core. Take a Nosler Partition, and put a plastic tip on it, and you'll still have nearly identical performance on game.
I don't believe they give better ballistics then either a soft point or a hollow point. A higher BC comes more from how the back of the bullet is shaped then any thing. As evidence for this, one only has to look at several old reloading manuals, and compare the old hollow/soft points to the new plastic tip bullets in the same shape that replaced them, you'll find identical numbers on both.
Further, if you look around you'll find with the exception of the A-MAX all the ultra low drag match bullets inveriably come in hollow point flavour. If there were truely any advantage in the plactic tips I would argue these types of bullets would benifit the most, and would be the first to have made the change when the tips became popular.
Its not to say they are a bad thing, because they are not, they may even offer some advantages, though I suspect its very minimal. But they are really no different in any measurable way then the older bullets they replaced, and for some manufactorers its a direct replacement with their older soft points in terms of performance on game. Truthfully I use them in some of my loads, and if I were completly honest I probably gave them a look see at the store because they do look cool, and there is nothing wrong with that. Though strangly enough the only reason I still load the noslers as a coyote bullets, is because they provide almost identical performance to the soft points I used to use.