Ok first off low roundhouse demon with the jabs buffered before hand is NOT harder than a TKD not even close. Maybe if you tried to TKD with low roundhouse but im pritty sure that is humanley impossilbe since the command overhead is 14 frames start up while the low rounhouse is only 7 and the command overhead TKD is hard enough.
Second, while it may be possilbe i can garuntee you that it is a million times harder to do a TKD on a pad and not on a stick. Its hard enough on my HRAP i cant immagine doing it on a pad.
but if your that determind there are a few tips i learnt that make doing this easier:
first off learn to do the lp tap with your index finger as demonstrated as the last method in Harmonaz’s video.
so you hit the mp with your middle finger then drum the jab with your index, then very qickly hit jab with your index finger again. this is better for consistancey becuase your hand has to move less as opposed to the double tap method.
second, to know your doing the jabs fast enough you should be finished the second jab while Gouki’s hand thats doing the chop is still behind his head. it is hard to do but just practice holding forward then drumming mp then lp then the second lp like i said and do it before his hand gets to the front of his head. that is the proper speed.
third tip is to do the forward motion as down forward rather than releasing the stick and tapping forward again.
so you do: forward mp, lp, lp, down forward, lk, hp
this also makes it so your hand has to move less, therefore doing less work and adding to the consistancey of the TKD
the last tip i have for this move is that the finish should be almost instantainious, as right after the second jab you should input down forward and drum short and fierce, do those 3 inputs like a kara move.
if your getting it so your demon comes out after the first hit of the overhead dont worry and keep pracitcing cause you almost have it, most of its muscle memory, you wont be able to learn it in a night and i would say that its probably the hardest move to exicute thats actually useful in a match in all of 3S (not including more than 2 normal takcles in the corner with urien).