Someone decided that wasn't quite kosher.
Indeed .. VFR/IFR had different OEI climb requirements for certification .. VMC was irrelevant. The difference in certification requirements at the time between the FARs and the ANOs caused folks a lot of confusion and head scratching .. but, for the Shrike (and some other Commander models) gave a nice increase over the US limit. As a side line point, the weight increases were largely substantiated by comparison to larger airframes with largely the same structures .. anything different had to be upgraded to suit.
Like you, I have quite a few most enjoyable hours in a bunch of Shrikes .. just like sitting out on a springboard at the local swimming pool.
I recall one flight at EN, many years ago and with a wry smile ... one of the local junior instructors came along in the RHS for the ride. In my normal manner of running checks whilst taxying along, the aircraft started wandering a little off the taxy line. Buggalugs, thinking to help out, but without discussion, stomped on the rudder to bring it back into line .. not the usual way to discover how the NWS worked. As I recall, I raised my eyebrows just a little as his face turned a bright red.