page, a 12 dB/octave filter isn't a tone control, and frequencies such as 50 - 60 - 75 Hz are too low to cause "boominess" unless they've been boosted to an absurd extreme. Boominess is usually caused by frequencies an octave higher than that or thereabouts. Beware of the temptation that when the tool you happen to have in your hand is a hammer, that the whole world can start to look remarkably like a nail. A modest shelving reduction (3 to 4 dB) at, say, 150 Hz and below might do more for you, while retaining the deepest bass notes and room tone that contribute to atmosphere and the sense of spaciousness in a recording.
Also, Schoeps' frequency response graphs are derived from free-field (on-axis, anechoic, plane wave) measurements. But when music is performed in rooms with rigid boundaries (walls, floor, ceiling), especially if any of those boundaries are parallel or nearly so, standing waves develop at relatively low frequencies, depending on the dimensions of the space (the frequencies at which the standing waves occur are related by their wavelengths to the room's dimensions). We're so used to hearing their effects that we may not be specifically conscious of them, but they give us a lot of our sense of the acoustical character of whatever space we are in, especially as we move around the room. And the thing is, the more directivity a microphone has, the less it will tend to register the effects of standing waves in a room. So a stereo recording that's made with supercardioids (MK 41) will convey less of that one aspect of how we subjectively experience a closed space, for better or worse, than a recording made with cardioids (MK 4) will do, all other things being equal.
It all depends on the room and what you want. I'm just saying that comparing the on-axis frequency response curves will show very little difference between the MK 4 and the MK 41 at the lowest frequencies but the resulting stereo recordings will show more of a difference in character than in amount.
--best regards
P.S.: The Lunatec V3 can be set via internal jumpers so that its low-cut filters are either 6 dB/octave or 12 dB/octave.