absolutely nothing if you are happy to put a litle bit of time into them, all i did with the half dozen Frosts ones i have was to remove the hump or ridge, or whatever you want to call it on the rear of the blade so it was flat, wrapped some W&D around a dowel and gave the thing a good sharpen up, they work fine.
Sure i use my Orfords all the time, but that is my preference, there again, i also use the Frosts ones i have on a regular basis as well, all depends what im carving.
At the end of the day it's all about preference, i prefer my Orfords, others prefer Dave Budds or Duncans knives, and that is their preference, but there are also a lot of seriously good spoon carvers in the world who use nothing but the Frosts knives, i suppose it also comes down to how much you want to spend as well, essentially the Frosts spoon knives are good tools, but could be so much better for a small redesign (i know it's not that simple), but isnt part of the fun of shrafting making mods to stuff to suit your needs and then using and therefore understanding the tool?