What is value in site aggregation?

[RobertFisher]

If one was to own 5 sites that were in a similar vertical and at some point decide that managing 5 sites was more of a pain than managing 1,2, or 3, is it possible to combine sites via 301 redirects and increase the overall DA, and for urls that are similar, PA?

So, we have site Hairbrush.com, comb.info, trimmer.com, hairmud.org, and barber.net:

Assuming that they have a DA of Hairbrush.com = 32

Comb.info = 36

Trimmer.com = 27

Hairmud.org = 21

Barber.net = 44

Is there any testing that has shown combining the first 4 would increase the Comb.info from DA of 36 to DA of 51, etc?

Is there any testing regarding the same, but with Page Authority?

Thanks

PS Assume other variables are equal. I also realize this could look as if they were all ECommerce, but what if they were service or bricks and mortar?

[RobertFisher]

OK, thought I would get a bite on that Question....I am going to run a test by setting up 4 sites in the same vertical with TLD's of differing extensions. Any suggestions on test parameters???