I own a IV.
I was careful in how it was selected back at the time of the purchase, but would, using todays gathered experiences, encourage a further demonstration in a Home System if possible to be achieved.
I heard a few IV's and V's many years ago in different systems at Uk Based HiFi Shows and at Dealerships. I was reasonably familiar with the sonic signature and impression these arms could make.
In the 90's at a show there was a demonstration room with Two TT's of the same brand, and possibly model from recollection. One was with a IV Mounted and the other with a V mounted. I can't be 100% sure if the Cart's were same.
As a result of extensive listening, I chose the IV as the Model and in the late 90's purchased one and had in use until approx' 2017.
Again from recollection, and having the disposable funds to purchase a V, without too much concern. There was not enough separating the two tonearms, in the demonstration environment and system used, to suggest the V was a level above worth aspiring to.
Around 2015, I was going to have the IV overhauled and upgraded and all conversations had were about lifting the Spec of the IV to the same as the V.
Shortly after this investigation, I was introduced to a Tonearm that changed my thoughts about Tonearms substantially, and the result of pursuing this alternative is, the today the IV serves as a Loaner Arm or is not used and on the Sub's Bench.