What you are feeling now is the coating that they use. It does not have that much to do with the material the keys are made of. That is probably the same as what has been used in other keyboards you may have owned. Some people like these kinds of coatings, others do not. It is really hit or miss. One thing that concerns me is whether the coating is actually durable. I read complaints about razer keyboards where the coating come loose after intensive use. Has the coating been upgraded or does this remain a problem?
There is a difference between the feel of ABS and PBT, though it is hard to describe. Some people will tell you that PBT feels more grainy/rougher/ more textured, and while this is true for the keycaps currently available, this has more to do with the production process of the key than the actual material that is used according to a couple of manufacturers. The actual difference in feel is more subtle than just surface texture, and there is almost no point in trying to describe it. Generally however, when it comes to feel, coating and texture also makes a lot of difference, in addition to the materials used.
