Originally Posted by AOK
Two is one and one is none. Get both and learn how to use both properly.
As for handheld... You don't need to spend $100's of dollars on a surefire flashlight (if you're willing and have the money more power to you, they are great lights). However, you can get a solid light such as a Streamlight ProTac 2 for around $40 or so.http://www.amazon.com/gp/aw/d/B00396S1Q2/ref=mp_s_a_1?qid=1359119924&sr=8-3&pi=SL75
It puts out 180 lumen, and it can be operated one handed. In addition, it is large enough to use as an impact weapon.
I agree I was thinking that the weapon mounted light would be good for a home defense option though i have plenty of light s at home one on the gun especially with a strobe feature might be nice to have.