The benefits of tighter component tolerances increase with filter order. A third order filter would benefit greatly but a first order won't.
My advice is to build the kit. Once you've done that, then you can experiment. Try to get the ideal parts list from the designer. The ideal parts list comes from calculated values. The first thing to do is wind your own inductors. These are the most non-ideal component. Then switch to non electrolytic caps.
Alan is right in that a crossover is complex business. I know because I've been involved in the design of passive and active filters - not for loudspeakers. The passive crossover for a loudspeaker incolves a lot of mental masturbation particularly for second and higher orders. Controlling the voice coil via passive means when it's impedance changes as a function of temperature, altitude and input power is darned near impossible.
Hence why active crossovers are the only way to go and that's where the LFR needs to go next.
