This is a higher power 900 MHz ISM band radio. Real life urban (San Francisco) range is 5 or 6 blocks with rubber duckies.
For the cyclic sleep thing to work you have to set up the other node as well:
atsm0 atst10 atlh29 atht29
In fact you don't really need the lh and ht settings on the remote node, just the SM6 setting, because its peer will never be asleep, and thus never needs a long initializer sent at all.
the barrier to getting really low energy use is that you apparently can't set the ST parameter (how long to stay awake for before dropping into sleep mode) to less than 0x10 times 100ms, which is 1.6 seconds during which it draws 48mA!
Unfortunately, when in cyclic sleep mode you can ONLY enter sleep by idling, as it ignores the sleep pin. :(