this feature is in all our dedicated chess computers, aart
)
they even realize to show search depth and evals without having displays (e.g. saitek leonardo or CXG computer).
i would repeat each move 3 times, and pause between each half move, so the
user can better watch it.
further the dedicated chess computers let the FROM square longer ON.
so that you have
LONG short, long short, long short rythm for each half move of the main line.
IMO a good idea.
the fidelity computers allow to SELECT the info via piece square a1-h1 .
with pressing e1-h1 showing 1st-4th half move of the main line.
so the user can decide WHICH move he is interested.
in a1-d1 pressed the fidelity computers show time, search depth, nps, eval.
by pressing on a1-h1 (when the program computes) the user can choose which info he wants to get.
but i do not think you really need this.
it is only senseful on SMALL devices with SMALL screen resolution.
on a HTC Desire or my china-touch-pad (7") there is much space under the board.
if you implement it, please make it OPTIONAL because i think serious players prefer the method you use in the moment with the main line.
IMO you could use ALL the space below the board. and make it optional to either show
game-score or search info or both (display splitted under board).
but i would not replace it .
make it an option to choose so any user can decide which feature he wants to use.