I’d like to suggest avoiding long excerpts

I’d like to suggest the practice of posting smaller excerpts. Long excerpts are less likely to be read and resemble articles in themselves.

Their comprehensiveness may render them irrelevant, and demotivate readers from going to the source before commenting.

IMHO an excerpt should generally have no more than two paragraphs, with exceptions for long reads (3500 words+).

For reference (and out of personal choice), 750 characters may be an ideal max, give or take.