I think JD is just making it clear that some implements won't work with the smaller CAT1 of the 2210. Many tractors have the smaller Cat 1, such as the Kubota BX and the MF GC2300 to name a few. You just need to remember that with some implements, such as Post hole diggers, you need to be a little careful with the model you buy. Most of this is due to the low stance of the tractor (which also is one of it's strengths, giving these a lot of stability on hills).
My tractor is the Kubota BX, and have not had any serious issues with standard Cat 1 implements. But I also know to be careful when buying a new toy....