The benefits to leaving the posts are obvious - I know none if any positives exist to deleting them.
Aye agree....I want to go back in time and look up threads on items as you said...they provide provenance. I have written some threads based on past forum items as this was the only way to get an understanding of when and what was done back then.
Thats why I created a timeline of my history with Cypher Hodl items and was also asked to do it from people that own my items.
https://bitcointalksearch.org/topic/cypher-hodl-timeline-5412935