I fired both at the range this morning. The Bodyguard is my EDC, for the past year, and I put a magazine worth through it every visit to the range. I have never had a problem it.
My 709 was new in January and it also has never failed to function in any manner. I shoot the 709 every week trying to gain a sense of its reliabilty before I carrry it. This morning, 100 rounds of WWB, 20 Silver tips and 20 Black Hills 124 Gr. JHP all fed and ejected perfectly.
The Bodyguard is a deep cover pocket gun and when I carry I no longer notice it's there. For me the 709 is as large a pocket gun as I could comfortably carry and I will most likely carry it in an IWB holster. Both are suitable for defense, but the 709 with the Black Hills 124 really packs a punch with a harsher recoil than the other ammo I shot this morning.
I believe the S&W Bodygaurd should be compared to the TCP738, and not the 709. You are comparing apples to oranges. I love my 709 and 738 too. They are reliable, and easy to conceal. I had the 709 and that is my winter carry gun. The 738 will pick up carry duty this summer when I will most likely pocket carry it. I like the punch of the 9MM round for self defense and I like the trigger on the 709. In my opinion, the 709 is the better choice, if you want to compare those two guns.