.Because I can put as many System sensor 2WTAB det. on one zone as my battery can support.
Hold up there.....In general that is wrong.
The panel manufacturer limit's the number of smokes on single circuit, typically it is by the model number of the smoke. This is especially true with 2 wire over 4wire smokes.
Most firelite/silent knight limit to about 20 smokes, see your install manual for the exact number.
Be careful with 23 smokes, check resistance on the circuit as well. There is a limit to resistance on the circuit sometimes as well (not including the EOLR)
The RSS-MOD being limited to one per panel? I doubt that. Obviously one per circuit.
I would really try to use more than one zone, for survivability reasons, troubleshooting reasons and notifcation. The owner/fire department could use a better idea of smoke in the house, say smoke on the X floor or X wing. It is the best way to go. Besides are you really looking to use a single zone FACP?
If you are using a burg panel that allows for one 2 wire smoke Fire rated zone, go with 4 wire smokes, If this is a resi retrofit and wiring is a problem, go wireless!!! There is a lot to consider and it can be easily executed, but you gotta plan a little.
ALSO, Your current on a two wire circuit will be limited. The A series system sensor smokes with the sounder draw a bit more than the non-sounder, check that out!!!