Well, that warning has been in the mod readme for like four months now, and I still don't remember hearing of any scenario that was actually made worse by using LWAMI.
Keep in mind, if you are just learning DW and don't really mind if some things are off or some weapons aren't exact at this point, don't worry about the mod, just focus on learning the game.
The mod does make the game harder in terms of how well the AI performs and the extra gameplay features that are added that you have to keep track of on top of the game.
Generally speaking, if you are totally satisified with everything you have experienced so far in terms of how accurate the game is, then don't worry about the mod. Once you feel you are looking for a challenge in MP or SP or have discovered a little gameplay thing that bothers you that the mod addresses (you can check the readme for 3.00B and I will have the readme for 3.00 hopefully done in the next 24 hours or so...), then install the mod.
Enjoy your game!
Cheers,
David