I'd probably put Whom Gods Destroy in my top five, right up there with "This Side of Paradise" and "What Are Little Girls Made Of?" That should give you some indication of my good/bad taste!
I, too, would have liked to have seen more of Garth, especially since he was on the "road to recovery" by episode's end. Maybe there's some fanfic...
Just watched the 1968 film "Madigan", in which our man Ihnat has a decent part. My wife couldn't identify him until she remembered the time I told her how Ihnat "vanishes" into a role and only then did she recognize him. He did the same thing to me in that "Big Valley" episode where Victoria teaches some outlaw to read. Ihnat played an outlaw in the guy's gang.
He also appears in a few "Mission: Impossible" eps, most notably as Stefan Miklos in season three(!) of that show.