Wordpress Posts or Pages - The Sticky Factor?

Depends on your workflow. For instance, I'm more comfortable dealing with posts rather than pages and the guy I used to work for was a stickler for pages.

Google like blogs.

From a structure perspective, the only difference is the directory they're cataloged into. As long as your URL structure is logical and search engine friendly, I don't think it'd matter what way you structured your content whether everything is a separate page or if everything is a post.

Being a blog platform at its inception, Wordpress likes to have a page that it can call a "blog". However it's entirely possible to have a blog page that is hidden from users of your site, whereby they only see pages. This is quite common infact for anyone that sets up websites for passive income.

So to answer your question, I think Google has no preference whether its a post or a page. If the length and quality of the content is good in Googles eyes, you'll rank well and have staying power no matter how your site categorizes your content. And yes, 50,000 pages would be harder to manage than 50,000 posts mainly because Wordpress automates post sorting. There are themes that are setup to use pages the same way but there is more manual sorting required than if they're done the blog-post way.

Blueboy

The built in indexing-navigation functions are all post oriented, you probably need custom plugins to better organize many pages.

There are plug ins that allow you to break out of the post indexing structure, one allows non wp pages to be inserted as the next page.

I Assume you have tried the static front page setting? The post index gets put on a secondary page in an awkward non abbreviated form.