I try to avoid the head on Merge, if at all possible.
Merging for me is usually the result of massive speed differential, instead of aircraft heading.
Whe the HO merge is forced though, I know I can't afford to take the HO as a single ping to my Yak is going to get my rad. So anytime I'm in a forward hemesphere merge, I use slight rudder/stick moves to keep out of the way. It usually works for me, but I do still catch a few in the face. Since the HOer is usually an La-7, if I surivive the HO, it usually takes a few seconds before I have the 6 shot, and he's running for ack.
-Sik