Would this be considered duplicate content?

Duplicate content is content that is doubled up on the same site, not across multiple sites.

Short answer is no, that is not duplicate content.

Make edits like you said, just to be on the safe side.. true, the term 'duplicate content' technically refers to same site content, but thats not saying that moving it from pt.A to pt.B will make your new site's content visible.. google already said "hey, site A has this content, and it's indexed. We're not going to index site B, which has the same content as site A, because we want to give our visitors a wide variety of content." That been said, I would totally rewrite. Once your old site has dropped off googles index (and the face of the earth), you can go ahead and put it on your new site if you wish.

@ Jinx1221 - I think a few major players in Article Syndication would disagree with you.

Well, Kauzmo, that wasn't really my point.. my point was, I would rather spend 10 minutes on a minor rewrite and be worry free, than wonder if my new site will be outranked by my old, useless site that I dont want anymore. I wasnt talking about syndicated content, because that's a whole other story. If you know some 'major players' who are somehow ranking well with syndicated content (dont ask me how), then, well, whatever.

I plan to rewrite all the posts, add some more content so the posts are a little longer etc. I don't plan to add them for a month or two, then slowly drip them out a couple a month, alternating with fresh, new content. Hopefully it will pay off!

If both the sites are yours and you want to get the results then use the cross linking method as this will provide you the better result and content will not consider as the duplicate.

This is how I would handle the old site that will expire.

1) Copy & paste each individual blog post into it's own text file on my desktop (offline).
2) Delete every single page on the old blog except the Index page
3) On the Index page header add the NOINDEX tag to tell Google you don't want the page in the SERPs:
4) Remove any existing meta tags in the header, only allow the NOINDEX tag.
5) After the old site is dealt with, on your PR4 site that your keeping add a link to the old site on the Index page pointing at the expiring sites Index page, to get Google to find the NOINDEX tag on the expiring site ASAP.
6) Check the SERPs to see If Google has updated by removing the expiring sites Index page from the SERPs because of the NOINDEX tag you added.
7) Once the old site is gone from the SERPs remove the backlink on the PR4 that was pointing at the expiring sites Index page, Google will think that old content your pasting on the PR4 site is all new content.

Some might say that's overkill, but I'm pretty sure you can remove that entire expiring site from the SERPs in a single day If you do the above steps in that exact order. That PR4 is most likely getting crawled at least once every single day by Google (that's the reason for the temporary backlink).

No. It is not a duplicate content. A duplicate content refers to the articles or posts that appear twice on a same website.

If you want to add the posts of Site B to Site A, why don't you stick a meta canonical link tag on the posts of Site B to let Google know that your preferred location of this content is on Site A.

We have just begun implementing a Conical Link Structure in our new website too see if we can avoid looking overly text heavy for a web design company.

Here is an article on the duplicate content by the Google Duplicate content - Webmaster Tools Help
"

• Syndicate carefully: If you syndicate your content on other sites, Google will always show the version we think is most appropriate for users in each given search, which may or may not be the version you'd prefer. However, it is helpful to ensure that each site on which your content is syndicated includes a link back to your original article. You can also ask those who use your syndicated material to use the noindex meta tag to prevent search engines from indexing their version of the content."

This thread is 7 months old. I'm pretty sure the OP has made his/her decision and moved on.