I agree with Philip that the use of an implied pronoun is less than
choice written English. However some sentences lacking verbs
and nouns or pronouns, called verbless sentences,
are considered choice:
-To all intents and purposes, none.
-Not anywhere near good enough to meet the situation.
-Probably so.
-Music to an author's ears, no doubt, and remembered this quarter century.
-Conversational awareness.
-But not the same.
The above were from a single issue of Harper's Magazine (September, 1950).
(Examples from
Understanding Grammar by Paul Roberts.)
It seems that omitting just the pronoun is a faux paus, but omitting more is "choice". Go figure.