The old Case Drott had the self leveling machine ,but as they got older they would leak oil badly and when left to set,would always be ready to tip over on one side when you came back the next morning to work.Alway parked it on the level or with cab down hill unless you wanted a ladder to climb up in the cab.
My guestion would be wouldn't a tilt bucket(with thumb) or tilt grapple for placing rock walls work also, compared to purchasing another machine.I do realize the machine setting level is a plus,but at what cost.
If you have the work i could see the size and ability of the machine being a plus,but attachments are still cheaper then another machine,unless size was and issue.
Also then you have to chance your tag line to add you new mcahine, will it be at the end of the line or the front????