I agree with ad,good mp replays in casual rooms just make themselves.I mean,everyone has that lucky time when they completely dismember their opponent in mp judo,but in sp,you have to plan everything and pend ours and hours on just one replay.

So in my opinion,sp is harder

People confuse time with difficulty.
Making a "good replay" in judo is like messing with the dm in sp.
I would like to see people make a good replay in mp, with the classic settings, easyer than in sp, since you can't edit.
Sp is just time consuming, because you work on it alot to make it look good.

In single player it is difficult because you need to edit the replay so many times just to get the desired move.

In multiplayer, it is difficult because you never know what the opponent is going to do.

It depends on your strengths and weaknesses.
To my experience, they're both fairly easy.

Multiplayer replays are harder for me because I try to do something cool then my
opponent ruins my move. Also, sometimes they quit before I can even save the fight
as a replay.

Multyplayer because you can't predict what he will do and it random mostly

Singleplayer is harder.

I know there are things like the Shift+Space or Shift + P or The edit button but it's still more challenging,and I know how I felt about making my first madman,i was like on the 9th cloud.

Heh.

It seems to me that multiplayer replays are harder, unless you don't really know what you are going for.

It really to me is the same, unless you REALLY dig deeper into the specifics. If you want to make a realistic single player replay, it's much easier because you don't have somebody doing other things that can mess it up, which makes MP a little bit harder.

Depending on what you want to do, will make one or the other harder, or even both can be harder.
It all is on what you are aiming to do in SP or MP.