I have three. An E grade, F grade and a H grade. The only time I ever had a problem was my own fault. The H grade did fan fire because I did not have the gun firmly mounted against my shoulder. It in effect bounced off my shoulder and fired a second time. Strictly my own fault. The gun has since fired several thousand rounds without any problem. The other tow never have had any problems and have fired near a grand each.
I do not know if Lefever had several different single triggers over time or just the one. I have not pulled the stocks to look at what I have and intend to leave them alone. I suspect he had only one trigger system and gradually improved it before he made it a catalog item. If it works leave it alone. The later D. M. Lefevers did have trigger issues but I suspect he was forced to invent a new system to get around the patents he left behind at Lefever Arms.
I think 900 for a decent Lefever, with a single trigger, is a decent buy. Unless there are hidden problems you should be safe.
