I'm not a big fan of automated message alerts. Say you're on a road trip and you get kidnapped. The phone is left sitting in your abandoned car. Your friends and family receive a text every day showing that you are at a stop. They don't know you're in trouble. You're better off manually sending a text each day letting folks know where you are and that you're OK. And, if the phone can send an automated text, it can send a manual text.
With that, my boss and I have been researching the satellite options. The SPOT devices don't seem to be very dependable. The ACR is the best for emergency rescue - it links to government and military satellites, so can pretty much always get your beacon delivered - the problem with it is that you cannot send a text, so you are likely to get a rescue helicopter when all you need is a tow (and you will have to pay for that helicopter). The Delorme lets you text like the SPOT, but is more dependable on the messages getting to the recipient. You can also pay a monthly subscription - only paying when you will be using the device - thereby saving costs.