I´m aware of the advantages of UTM. I found that it´s a matter of being to used to a format and having a map with the right grid. When it´s actually about searching a circle with a certain radius the GPSr shows the distance without any calculation. When it´s about searching a rectangle it´s just as easy to say start at point X go 00°01´ instead of 1000m (I know it´s not the same but it doesn´t require much math either). Eventually it all comes down to being used and having the right maps (using Lat/Lon on a UTM grid or vice versa is a PITA for sure). It may also require slight adaptations of the search patterns but it should be feasiblle.
I have my preferences and I´m perfectly comfy when you use what works for you.