I know the rules with Delta's RPU salivating at the opportunity to catch this activity when it is done solely on their airline.

However, is it the same taboo to use a different airline to make it work. For our example lets say that we do not throw away any "legs" but just travel at two different times.

ie.
DL ATL - IAD 10/26
DL IAD - ATL 11/5

NW IAD - ATL 10/29
NW ATL - IAD 11/3

Of course, many wish to know whether or not you will get "caught" using two different airlines to B-2-B?