Make a webplayer or standalone build of the default AngryBots project. Change lightmapping mode to Iterative and make another set of builds. Compare the build sizes. My results:
Angrybots WebPlayer build with baked Beast lightmaps - 19 MB, with Enlighten - 23 MB
Standalone build with Beast - 79 MB, with Enlighten - 130 MB

Since it's a different technology, I understand differences are to be expected, but this is quite significant (on mobile it might matter a lot)

This is a regression in terms of generated player build size.