Another interseting tidbit is:
http://www.pmengineer.com/CDA/ArticleInformation/features/BNP__Features__Item/0,2732,135186,00.html
I must let it be known that my above post, and probably the vast majority of my postings, refer to the Minnesota Plumbing Code. The MN Plbg Code could be considered a (rather restrictive) cousin of the UPC, such key differences are not only based on environmental conditions to MN, but also progressive theories of health sanitarians dating as far back as the 1870's. (Statewide licensing of plumbers began in 1933, many municipalities had ordinances regarding licensing and code predating the 1870's.)
I've heard of only one SoVent system allowed in MN, dating back to the 1970's.
I have been transitioning into becoming more knowlegable on the UPC, which is the code in ND. MN plbg code allows more of an 'engineered system' style code in relation to venting, whereas the UPC is rather restrictive in vent loading. Commercial kitchens and potable water protection are where MN is much more stringent.
Another key difference is that MN requires a manometer air test at final inspection. Plug the main cleanout, cap the vent terminals. The DWV system must withstand 1" WC (water column) pressure with all fixtures connected, the test time-limit is for the duration of the final inspection. Plan reviews for all plumbing in buildings of public use (gas stations up to hospitals) are required prior to commencement of work.
I appreciate reading about alternate methods allowed by other codes.
As we all know, there are alot of ways to 'skin a cat'.