While old school piercing does have the advantage of being predictable, it fails unless one is willing to make the assumption that the widely accepted techniques are the best. For example, take the debate about new piercing tools such as dermal punches. Many new school piercers believe that on some piercings they result in faster and better healing than a needle. Old school piercers may disagree, saying that the tool is unproved, and belongs in the medical community where it began. (Of course, none of these things are set in stone - Thirty years ago the notion of using a 10ga needle rather than a piercing gun would have horrified most "piercers" at the time.)
Piercers are not only divided on issues of technique - for every piercer there is an invisible line determining how far they are willing to push the style and difficulty envelopes. To make a generalisation, old school piercers tend not to push this envelope. But for those new school piercers that do, one also sees extreme piercing and technical piercing start to emerge.
A technical piercing is a piercing which is has a technically difficult procedure (from the piercers point of view). For example, one piercer well known for his technical piercing is Jon Cobb - the uvula, the trans-scrotal piercing, and the base-ampallang are good examples. What separates these piercings from others is that they are very difficult to perform, and require a higher than average ability to plan on an anatomical level. Technical piercings are probably appreciated most by people who really understand the piercing and piercing technique in general. A technical piercing takes time to plan, practice and dry runs to perform safely, and skill to do. Surprisingly, often skill as a piercee is also required - they must be able to sit still during a difficult procedure and even assist in the case of contingency. In the case of a potentially dangerous piercing, extreme trust is required between piercer and piercee.
An extreme piercing does not necessarily require the same level of skill as a technical piercing, but the lay- person will often make this assumption. What makes an extreme piercing stand out is its character. A good extreme piercing should make someone, even inside the piercing community, make a double-take when they see it. The majority of piercings of this type are unique surface piercings such as forehead, spinal, knuckle, and similar piercings, but they can also include visually unique versions of old school piercings (for example, five spiked labrets rather than a single beaded one). While the point isn't usually to shock, that is often the result - the point is more to add flavour to the visual world. An extreme piercing fan generally values the unique nature of their piercing just as much as its specific aesthetic value.
To describe these divisions quickly, imagine old school piercers as a reliable old car - it won't necessarily get you everywhere, in the most efficient way, but as long as you want to get to a typical place, you'll get there in an acceptable amount of time. To extend this analogy, a new school piercer would be an all-terrain vehicle with some kind of hybrid fuel engine - it will get you to more places, and by varying the way it works, will do it more efficiently (but there aren't many mechanics that can service it). As far as technical and extreme piercing, technical piercings are the "nerds" of the piercing world, and extreme piercings are the flamboyant punks.