Even I didn't see too much of LOU GRANT because of the night it was on (Mondays, at 10pm , if I can think back that far -- which, for some reason, was a bad schedule for me) but for what I saw of it, it was fairly good -- for the time -- and the unusual concept of a sitcom character in a drama mostly worked, in large part because of Ed Asner (and his Scorpio Rising "boss" vibe). And it was a decent production, and got a bunch of Emmy awards like its parent series.
Certainly, LOU GRANT pulled it off better than either RHODA or PHYLLIS; even though RHODA managed to eke out a 5 season run, after the series' flimsy identity was lost, its big ratings dropped precipitously, and PHYLLIS died in 2 years partly because much of the cast did the same....
Predictably, Rhoda lost her side-character snarkiness once she went center-stage with her own spin-off (and Brenda became the "loser" in a way Rhoda never really was, even on the MTM Show) while PHYLLIS tried to maintain Phyllis' original neuroses and not make her overly sympathetic, but somehow it just seem to flounder.
Once MARY TYLER MOORE cancelled itself in 1977, Gavin MacLeod spun-off (with Spellingesque "success") to LOVE BOAT, and Betty White and Georgia Engel teamed up for another MTM Enterprises sitcom called THE BETTY WHITE SHOW where Betty played a none-too-talented actress in a TV cop show-within-a-show called "Undercover Woman" and an obvious satire of Angie Dickinson's POLICE WOMAN (which reportedly none-too-pleased Dickinson who stormed out of an early screening (apparently somewhat facetiously) and growled at her pal "if your hair gets even one whit blonder..."). But THE BETTY WHITE SHOW didn't make it --- in fact, I almost never saw it (I think it was also on Mondays before LOU GRANT) and its being shot on cheapy-videotape somehow decreased its appeal (although that worked for the Norman Lear sitcoms).
LOU GRANT was the spin-off/sequel/MTM cast show that was arguably most successful, and even it was cancelled after 5 seasons due more to Asner's outspoken liberal politics in conflict with the increasing Reaganistic conservatism slipping into the '80s culture (i.e., calls from on-high were made to the network brass) when criticizing Reagan was almost considered blasphemy in America.
In 1980, Ted Knight starred in the horrible TOO CLOSE FOR COMFORT sitcom when they were frequently casting unfunny people in poorly-written TV shows, where he marinated until his death in 1986, the program retitled "The Ted Knight Show" at the eleventh hour, presumably for pre-mortem vanity purposes.
I stopped watching MASH after its first three or four years because it was always against something else I wanted to see more. I rarely saw TRAPPER JOHN partly because Pernell Roberts was hard to take as a series regular (unless he's Adam Cartwright) and the sequel series AfterMASH was just too weird that I never really gave it a chance.