I have a 121.5 Mhz ELT and was planning to upgrade to a 406Mhz at some point in the future. I figured between mobile phones, multiple GPS and talking center this wasn't something that was at the top of the list. A little factoid changed my mind.
- A 121.5 Mhz Elt will narrow the search area to around 30,000 to 100,000 square miles depending on the altitude it is detected
- A non-GPS 406Mhz ELT will narrow the area to 12 square miles
- A GPS enable 406Mhz ELT will narrow the area to 0.75 square miles or less
Also, always keep your mobile phone on when in flight as it will ping cell towers and the SAR team can use that to pin point you as well. They had a a rescue where the pilot was stuck upside down in a field and his unreachable mobile phone was on and they were able to find him based on the cell towers. It did take them around 12 hours to find him though.