I've trialled both indigosat and spider tracks.
indigo sat had extremely powerful reporting. whilst the panel mounted systems offer 2 way texting, the portable units didn't. it used the immarsat system for communicating. it also could transmit 'digital status' (ie weight on wheels etc - eo or similar required)
spidertrack spiders are smaller and some models have the advantage of being able to send and receive text messages with certain blue tooth devices - from memory it used the irridium system for communication. all reporting was accessed from the web. the spider watch is a good idea - if the server doesn't receive a 'landed safely' signal it starts alerting procedures if updates are not received.
in our application the satellite texting and portability made the spiders the best option.