Well, the original arcade game was digital, but you're playing through mame. Mame now has a very good analog to digital joystick, comparable to what the u360 does in firmware: a 9x9 analog to digital grid. (Mame has the deadzone and saturation settings; the u360, though, can adjust each row/column height/width.) A tron grid of:
788888889
4s88888s6
44s888s66
444555666
444555666
444555666
44s222s66
4s22222s6
122222223
would give you small diagonals. (Increasing mame's saturation setting toward 1.0 will shrink the diagonals, and decreasing it will increase the diagonals.)
So the fact that POTs are on your joystick actually gives more flexibility than if it had microswitches.
However, other issues will come up. Usually, analog sticks, including flightsticks, have softer/weaker springs and a longer throw than digital sticks. Again, that's usually, as "correct throw" and "correct spring" vary from person to person and game to game.
Test playing tron with your flightstick. I'd set the above map by adding -joystick_map 78.4s8.44s8.4445. for tron. (That number sequence is mame's shortcut for the above map.) See if you can play the four levels, and if the diagonals are easy or hard to hit on the correct levels, and if the throw it's too long, and if the springs are strong enough.