I'll probably take some heat for this, but...if you are using a remodel type fixture, then the j-box of the fixture is accessed only by removing the recessed fixture. So I don't see a problem if you put another j-box in the ceiling accessible thru the same hole. However, I did see a UL listing once on Lightolier recessed fixtures that said if the hole was not at least 6" in diameter, it would not be listed for "feed-thru" wiring; i.e. you couldn't use that hole for the large j-box if the recessed light is less than 6". The 1100 series takes a 6 5/8" hole. (And Lightolier 1000 series, 5", and 2000 series, 3 3/4", are labeled suitable for feed-thru wiring, but they're not unless there is access from above!)
