The Dive Alert site has a pretty clear description of which combo octo/inflators use which fitting.
Regular old LPI hoses, of all brand regulators and BCDs are interchangeable.
Combo inflators/octo devices are different, and come in two flavors:
The ScubaPro Air 2, Tusa Duo-Air & Atomic SS1 are one type.
SeaQuest AirSource, Zeagle Octoplus, Beauchat Venturi, U.S. Divers Air Mic & Oceanic Air XS use the other non-standard LPI connection.
LPI Connections -- 3 types