Posts vs Pages - Wordpress SEO question

[Shootingtime]

With the help of a friend, I am changing my website's theme and upgrading my website. Currently the site, which is a page based site, gets decent traffic. It is built using a "silo" system. It has silo (topic) landing pages, then subpages.. hence the url structure is ...../silo-topic/page-name.

My buddy swears by using posts almost exclusively and this scares me. I will still be able to maintain the url structures if I changed all the pages to posts, (/silo-topic/page-name.... will now become .../category/post-name/) but I fear that some of my heavy traffic pages will lose value quicker as a "time sensitive" post.

Some expert claims that, for his website, he creates his articles as posts and when a post starts to rank really well, he will change it to a page and use a 301 redirect to the new page. The new page's content won't get watered down by comments and should be a "timeless" fixture on his website. I understand his thinking.

Here are the questions I have:

1. Should I change all my pages (articles) into posts and cross my fingers? My urls will stay the same; the new posts will just become time sensitive/dated material.

2. Should I take my heavy traffic pages and keep them as pages? I would have to change the urls due to the fact that most of the new sites articles will be posts and take over the silo url structure.

Thanks for any and all input!