[smartdude1212]

If you so choose, mention something about hotkeying this:

s = left
d = down
e = up
f = right

along with the use of the numpad (4286). This would allow any keyboard (as far as I know) hit things like hands (vrofl) or just really close together arrow/jumps (48th-to-jump in Legendary Etude, for example). Whereas arrow keys + numpad hitting a hand might mean a miss on some (not all) keyboards.

Also I don't think I saw 2 hands 3 fingers with the left hand on arrow keys (or in my case sdef) and the right hand on the numpad. This helps a lot with crossovers and other awkward patterns.

Pros with 3-finger:

Runningmen, trills, stream, consecutive jumps (but not jumpjacks) are easy to hit
Depending on what a player has figured out as to what they can do with 3-finger in the format I said, jumpstream is much easier
PA is relatively good, though this partly relies on the player and their rhythm too

Cons:

Jumpstream
Really awkward patterns
(some would say) You reach a pinnacle of skill and it just stops there

Combined with spread:

mega pwn