I've never used WASD. Been playing FPS since Wolfenstein, and you used arrow keys to move, and ctrl to shoot. At some point I remember setting up Doom (or Doom 2?) to aim with the mouse, but I was still using left ctrl to shoot and alt to toggle strafe movement (you strafed instead of turned when moving the mouse).

Enter Quake 1, +freelook. Upgraded to ctrl to shoot, z & x for strafe L/R, and space to jump. I've always used the left mouse button to +forward, and the right mouse button to +back.

At some point during the Half-Life 1 years, I upgraded to my current config, which I call ASDF.

Middle keys (SD, so ring finger and middle finger) are used for strafe L/R, outer keys (AF, so pinky and pointer) are used for +zoom (A) and +attack (F). Mouse buttons are still used for +forward and +back.

I like having my fingers on home row, since I'm a programmer anyway, and it's a very natural position for me.

Now, with this setup, I'm aiming with the mouse (right hand), and shooting with the left hand (F key).

ON TO MY QUESTION:
Does anyone else do this? Does anyone think that there's a possible aim disadvantage, due to both hands being involved for aiming and shooting? That "move the mouse, click" would yield better aim?

I've been using my ASDF config for soooooo long, WASD just seems impossible to get used to. I would have to relearn the basics all over, to get new muscle memory. The most time I've spent trying to convert is a few hours. After that I switch back because WASD is so frustrating.

Using a page like http://deadmen.us/quake-reflexes.html I average about 270ms reaction speed when using the keyboard, and about 310 when using the mouse. 40ms slower with the mouse seems pretty significant. This could be due to my muscle memory (I'm using to using my left pointer finger on the F key, so I respond more quickly), or it could be because I have a nice mechanical switch keyboard, and the actuation is easier/faster with the keyboard than it is with the mouse (a razer deathadder).

I'm mostly looking for input from players who have used a scheme similar to my ASDF scheme extensively, as well as WASD. For those of you who have, which do you prefer, and why?

I have average aim in duels and CA games right now. 30/35+ lg and 40+ rail on a good day. Rarely under 30 lg or under 30 rail.