Linear Advance - does it make sense using an 8-bit board?

Hi, after updating my Cartesian XY to Firmware V1.0.4,
I did first steps with linear advance, but there were no real difference between test pattern lines.

Here are some basics:
- Rumba board, 8 bit
- autolevel and distortion correction activated
- microstepping 16
- configuration.h:
    #define USE_ADVANCE 1
    #define ENABLE_QUADRATIC_ADVANCE 0
- part of gcode test pattern (L factor from 0 to 60 step 5, relative Extrusion coordinates)
    M233 X0 Y10 ; set L-factor
    G1 E1 F1800 ; un-retract
    G1 X111 Y117.5 E2.1553 F1200 ; print line
    G1 X191 Y117.5 E4.3105 F4200 ; print line
    G1 X231 Y117.5 E2.1553 F1200 ; print line
    G1 E-1 F1800 ; retract
    G1 X71 Y122.5 F7200 ; move to start
    <next test line>

- with 100% speed the extruder moved backwards at the third line part
  (It seemed like the extruder uses absolute coordinates instead of relative (M83 was sent),
    Extruder position was the same at all line starts, despite extruding manually clearly reacts as relative)
- only below 45% speed the extruder moved forward,
  but regarding L-Factor there was no difference at the speed change areas of the line parts.
- also tried 25% speed, no difference.

In general: Does it make sense to play with linear advance using a 8bit board
32 bit is an option. Which one are you using?

Thanks for your help!