Here's an update... I just got back from the proshop. I got there and off came the Hostage and on when the Whammy! So I did the best I could to follow the directions, but when I got to the part about timing the Whammy I got lost... So I took it to the shop owner, who thought she knew what the deal was, but then called the company.... too make a long story short, I have the Whammy on my bow. I think it's timed, but I really don't know. My fletchings didn't pop off today, so I assume that they're clearing. I thought about paper tuning, but I didn't have a stand or paper!

I tried to adjust the height of the rest and the horizontal position to get the arrows to shoot in about the same place as the old rest... but it was fruitless. I was consistently hitting high and to the left. I can't really move the rest any lower since the prongs are already contacting the shelf. I have no clue what I'm trying to do when I adjust the horizontal position... I was trying to get the string, the arrow shaft, and my line of pins to all like in the same plane, but I'm sure that's not the way to do it. I tested at both 10 and 20 yards and after all was said and done, I had my arrows landing in as good of groups as you can ask a week-old archer to shoot! I guess I'll call that "tuned"
As for the prongs, Yep, I definately would like a deeper groove. I tried to rotate the prongs up to make it a steeper V, but that just makes the gap too large, so the arrow falls through!

My rest definitely whacks the shelf and I have two little spots of chipped finish to prove it! I would have put the plastic prong covers on that came with the Whammy, but they're sooo stiff that it is impossible to slip around the high curvature at the end of the prongs! I'm going to try to soak them in hot tap water to see if they soften up enough to get them on the prongs.