Italia458.
I think you have misunderstood something about PANS-OPS.
According to Doc 8168, you cannot choose to operate an aircraft in different CAT (reduced speed during circling in order to use lower minima, etc).
8168 Vol.II states: "An operator may impose a permanent, lower landing mass, and use this for determining V(at) if approved by the state of the operator. The category defined for a given aeroplane shall be a permanent value and thus independent of changing day-to-day operations." (Part I, Section 4, Chapter 1. 1.8.6)
and
"The design of procedures in accordance with PANS-OPS criteria assumes normal operations. It is the responsibility of the operator to provide contingency procedures for abnormal and emergency operations" (Foreword 1.5)
Hope this helps
Regards
LIN