wonder if I'll ever become adept enough to find this move ...

|10.m9

this is basically what the Achilles Defense looks like ...

1 to the inside, 4 towards the near border

|1.e8 2.f4

it can be used against white pegs in these positions ...

|1.b7 2.x2 3.c7 4.x3 5.d8 6.x4 7.e8 8.x5 9.f9 10.x6 11.g10 12.x7 13.h11 14.x8 15.i12 16.x9 17.j13 (and so on, diagonally)

it's not a "perfect defense" -- it needs at least one "supporting" peg

for example

|1.e8 2.f4 3.h5 4.i5 5.j6 6.g4 7.k4 8.h6 9.h7

this is the Medcalf defense

|1.g10 2.h6 3.d6 4.d4 5.e4 6.f3 7.g3 8.i4

one sequence when they play "three away" ...

|1.m13 2.m10 3.l11 4.l8 5.n10 6.o8 7.q8 8.q7 9.o9 10.m9 11.r6

note that "they" win if there is a peg at q9, q11, p12 or n12

here's an attack derived from the Medcalf defense

|1.g10 2.h6 3.h8 4.i8 5.d6 6.f7 7.c8 8.e9 9.d11 10.d12 11.c13 12.e10 13.d10 14.c11 15.b11

the defense?

|1.g10 2.h6 3.h8 4.i4

now, if 5.d6 6.d4 7.e4 8.f3

here's an interesting three away defensive sequence

|1.q14 2.q11 3.r12

white is expecting that black will play S12, but instead

4.p9 5.s10 6.s8 7.s6 8.r6

With the exception of your first post, all of your variations begin with move 1. It is unclear how they pertain to this game. If you wish to continue a variation over multiple posts, you must include in each post all the moves beginning with move 10, or wherever your variation from the game begins. An easy way to do this is to produce the position you are interested in on the board, then select and copy all the moves highlighted in red below the board, including the vertical bar, and paste that into your comment. It is recommended you use the Preview button and click on the moves in your intended post to make sure the positions you are creating make sense before you press the Comment button.

After |10.m9 the bot line is 11.p9 12.p7 13.e11 14.f9 which evaluates as a strong advantage for black. So yes, you're right about that.