I don't do doorway pages, I add static pages geared to what searchers are likely to be looking for, particularly if it's a dynamic site.
I've seen that -1 for subdirectories, but not altogether consistently. On one site now that's a PR5 on the high side, I added 3 pages that are in /directories/ that'll be separate sections of the site, like departments.
The pages in the directories ended up PR5, while the pages in the root were 4. The shopping cart is excluded in robots.txt to keep it out of the way, and there are no links from outside the site to any interior pages; just the index page has links in.
Those pages are not linked up the same as the rest of the static pages, which are all in the root. A couple of days ago some root level pages were 4, some 5, and out of those 3 directory pages, one is now 4 and the other two are still 5 - the linking within the site is a little different on one of them.
On a couple of other sites directory and root pages are the same, 1 lower than the index page. On one that's PR4 they're all the same down to /directory/page.html
It's probably different on small sites that only go 1 level deep than it is for large sites. I'm inclined to agree with caine that it depends on the linking in the site.