ER said:

"Also, these macro projects would attract a lot of attention...maybe not a good thing."

On the other hand, if you can build a Dyson Shell, not many lower levels
of intelligence are likely to mess with you just from seeing what you can do with and to an entire solar system.

I once had a dog which weighed 137 pounds. He was a very kind and
gentle dog and never once got in a fight because every other dog took
one look at him and said I ain't messin' with that! Dyson Shells might be
a slightly larger version of this philosophy, though of course that would
be the side benefit and not the main goal - then again, who knows what
an alien mind with lots of ability and resources might have in mind.

Then ER said:

"I know Socrates and I don't see eye to eye on this, and a lot of the thinkers on this subject agree with his concepts of giant brains and other Vernor Vinge-type KII and KIII civilizations.

"That's why I was wondering if the IRAS searches had turned up any promising leads yet."

As much as I am very intrigued with Dyson Shells and all sorts of mega
astroengineering projects, I am willing and interested to see the other
side of things at the small end of the scale.

Related to this idea, one theory as to why we haven't found ETI yet is
that all the advanced ones are living in virtual worlds buried deep under
planetary surfaces for their protection.

In this interview with Hugo de Garis, a big advocate of Artilects, he also looks into the really small scale of things like femto-tech and plank-tech
that would make nanotech look like stone knives and bear skins.

http://machineslikeus.com/interview-hugo-de-garis.html

So maybe the really advanced ETI are working and living at scales that
would boggle our tiny chunks of gray matter as much as humungous
space structures do. They could be enfused throughout the Universe
moving through quantum reality like we walk down the street - even
easier in fact.

Maybe this is all a pipe dream, but I keep thinking of the "experts" who
used to say man would never fly and such.