I used Ken's qed in pre-Unix days. I understand its big departure from the original was regular expressions. Unix ed was the same, with multi-file capability dropped. Evidently the lost function was not much missed, for it it didn't come back when machines got bigger. I remember that fairly early in PDP-11 development ed gained three features: & in the rhs of substitutions plus k and t commands. (I'm not sure about &--that was 50 years ago.).

With hindsight it's surprising that a "minimalist" design had m but not t, for m can be built from t but not vice versa. A cheat sheet for multics qed is at http://www.bitsavers.org/pdf//honeywell/multics/swenson/6906.multics-condensed-guide.pdf. It had two commands I don't remember: sort(!) and transform, which I assume is like y in sed.

Doug