Is Trusted IP's (Friends) Secure?

We are getting ready to deploy about 15 Airlilnk RV50’s in the field to read mesaurement devices. I have tested both a VPN configuration and a “Trusted IP’s” configuration. Both work just fine but the Trusted IP’s configuration is much simpler. I want to recommend using Trusted IP’s but I was interested in whether or not there were any significant security issues associated with this type of configuration. Thanks for any input!