I don't see much difference between the 3" and 4", they both shoot better than I am capable of doing. I do, however, like shooting the 3" more than the 4". That is just me.
I purchased the lower 4" new, the other two were imported from Israel. My local dealer at the time (mid 1980s) made several buying trips to Israel and brought back a number of 547s, FALs, Mauser 98s and others I don't recall. The FALs were select fire and upon arrival in country he had weld a small bead on the receiver to prevent the selector moving to automatic fire.
I keep an eye open for anything about the 547 for posting but have not heard about a mid-East copy. Interesting thought though. In the 1990s I frequently flew Air France and the police in CDG carried a revolver tethered to their belt with phone cord like cable. Only the butt and hammer were visible from the holster, but the hammer sure looked like a 547. Like you, I hope others will post observations of the 547.