If what is normally controlled access areas are made available to bots
while anyone else executing a search would be left out, without
registration, that would not be good as it would effectively be a form
of cloaking.  A number of large sites had issues with that not too
long ago.

I can't tell if that is what is happening although it may be happening
but not something intended but it should be looked into to make sure.

As for the search links, other than the resulting snippets from an
executed search being a bit shorter than an average blog's index
page's abstracts of various articles, I don't see a lot of
difference.

Just get rid of the ability to alter and resubmit the search and
increase the length of the abstracted text for each article.

It would effectively be the same as a common index/category page with
links abstracts of and links to the various listed articles.

of abstracts might be the first search result and then the actual page
indented off of that or vice versa.

There are a lot of searches executed for my cass-hacks site where the
abstract page is listed as a parent of the page that has the actual
information on it that one is searching for.

Although my entrance and "category" pages are not dynamic like your's
are, they look very similar in content, other than yours having search
type thingies on it instead of just looking like a category index.
Get rid of the search thingies, beef up the abstract/snippets a bit
and you should be good to go.

Craig