Here are two links:
http://www.backyardflying.com/secure...6355207.2.html
http://www.backyardflying.com/secure...6355200.2.html
Range is the big one. From what I read, the Picos are better suited for indoor flying. The reduction of range helps with glitching indoors because the Rx doesn't have to deal as much with all the weaker reflected signals.
Where I fly outdoors, all use Naro's without problem. It depends on where you fly. Some people have all kinds of problems with glitching using these and others not. It may depend on the way you set up the plane too. I've had to route antennaes out the wing to get rid of glitching.