actually, LEDs are current source device, so stable current supply is the critical issue here... most of these kind of 3W, 5W,10w LEDs should be partnered with proper drive electronics..

so yes, these LEDs need superior drive durrent control.. or else you will tend to overdrive them if just plugging into batteries+resistor control (which is Voltage source design)...
of coz, using Cree and branded type, the ability to sustain current overdrive is better than those non branded china types high power LED modules.. so I guess one could argue buying branded "US or japan" type has pseudo overcurrent protection built in..