I had thought of getting a Mk iii Hunter (long barrel) to complete my collection; which would give me two Mk iii short barrels (Target and TALO Hunter) and three long barrels (Mk ii Government Target, Mark iii Competition Target and {a new} Hunter). It seemed to give me the best of the available Ruger .22lr pistols.
I know the arguments of field stripping the Mk iii's and the unneeded parts on the Mk iii's. I ignore the unneeded parts and learned to field strip the older models, so Mk IV doesn't offer a lot of appeal.
In fact, I thought about the economics of another .22le pistol, even a discounted Mk iii Hunter. I try to get to the range a couple of times a week; being retired, it's easier to do. But, even with a couple of trips a week, it's difficult to shoot all my .22lr pistols as much as I'd like. Didn't pay a lot of attention, just bought a pistol I wanted over time as they became available; now have 7 .22lr pistols.
If I were starting over, I'd wait a year; then collect the Mk IV models that appealed to me.