Just to note, while there is a substantial difference in power between a PLB and a SEND, remember that there is also a huge difference between a geosynchronous satellite at 22,000 miles vs the SEND satellite' low earth orbit of 485 miles.

OTOH, with overhead cover of a heavy forest, 5 Watts will punch through whereas 1.6 may have a more difficult time, although in actual operation I don't recall any significant failures in this regard.