In som eways I can relate to Igor's worries. I do use and am trying to extend OACS 4.x series. I am planning to put into use within my small collective for a few things, possibly extending it to department-level intrantet system.
I am also considering moving my old Apache/Perl home page to ACS. But I am not sure I would want to use 4.x for this.
My concerns, however, are of a slightly different nature. If one recalls, one of the arguments for AOLServer that Phil used to give was the fact that while you can build a database-backed website, you do not have to tie yourself to the database 100%.
If I am not greatly mistaken, the beauty of 3.2.5 is that even if Oracle/Postges are down you can still use static content of the site. Bboard/commetns will not be available, yet you plain .html page will be there.
It is not possible (or at least I don't know of a way) to do it in 4.x, as all the URLs in address bar are not 'real'. If a database ever fell over, anybody hitting a page on a site will get something like 'Could not allocate a database pool, yada-yada-yada'.