In my opinion we should aim at very stiff boots, with very soft springs, which would mean that the 225 would be probably a bit too soft. But if your weight is about 60kg's even these boots would be enough. Depends on your physical attributes
We have done the ACSS very soft in comparison to other systems but finally some stiffness is still needed. I mean:
1. to learn EC, the softer, the better.
2. To get best from the EC, and snowboard sensation, medium spring system would be nice.
This is my opinion and this differs from the others, there are many who like no springs at all, many who can easily EC with blocked boots, and a lot of ACSS followers.
All depends on your skills.
Generally, the stiffer boot, the more straight your board reaction is. The softer boot, the more comfortable you are, but you loose the top speed control.
This is a reason why racers use really stiff setups. As we don't go that fast in EC, we need no that hard shells nor that hard springs.