Is there an alternative to Find my iPhone to track a lost/stolen iPhone with SMS support?
If you lose your phone or it is stolen, it is likely to be miles away from your home and just knowing this allows you to use the 'Find My iPhone' feature on www.me.com to remotely wipe (and/or kill) the phone, or to make it bleep and put up a message if you realise you've left it at your friend/family-members' house.

An SMS-based app would require you to have another phone to find/lock/wipe your iPhone, plus there's always the chance that you forgot to run the app following a reboot, or that it crashed.

"Find My iPhone" is built into iOS, so you don't have to remember to run it.

Although 3G does use up more battery than 2.5G or 2G, this is not the primary cause of battery drain in a smart phone - try quitting some your apps to find out which one is draining the battery.

Also, read through the comments on the link you posted - there are some real unhappy users there who post about the problems. I wonder how many Android phones are out there that somebody could SMS-spam with the magic command to remotely-kill their phone....