[7magtime]

I've only took a frontal shot once with archery and it was a few years ago on a mulie buck I had been after for awhile.
He came down a treeline I was set up in following a doe. He stopped at about 10 yards to look over at the doe and I sent an arrow into his bottom 1/3 dead center.
It was one of the most dramatic and quick kills I have witnessed with archery gear with him being down inside 40 yards and probably less than 10 seconds from the shot.
After the first 20 feet it was like someone started pouring red paint on the snow, it was quite the blood trail.

I had passed on frontal shots before but in that circumstance it was a close shot and the buck had no idea I was there so I had time to pick my spot carefully.
I was using fairly heavy arrows and cut on contact broadheads, the broadhead was found against the skin just shy of the rear hip.

Just my experience, like others have said every opportunity on a frontal shot can have different variables which will affect the outcome.....