+1... the wood combined with the pickup placement gives these bass spec's their classic 60's versus 70's type tone:
LG/60's..... round low end, nice push/growl in the low mids, and a polite upper mid response (no grind) that results in a bit of space between the treble and mids... sweet, airy top end
LM/70's... big, extended low end, polite low mids (not much growl), accentuated upper mids (lots of grind).. that results in there being very little space between that upper mid grind and treble response... grindy brightness.
The DR Lo Rider steels will magnify that upper mid grind with the LM, making it sound very ganky and 'old school' (especially in passive mode). The DR HI Beams (which have a hole a mile wide in the upper mids) moves the LM to be a bit more polite and airy up top. The DR Lo Rider Nickels just SIT on that wonderful lo mid growl of the LG to my ear, and still provide that nice sweet, airy top end.
Nice stuff... you can kind of hear this in my old iComposition clips comparing the LM and LG.