You can find R7 measurements in KEF website and in Spinorama.
-6 dB below reference level is at 35 Hz, very far form what is needed for a proper listening in cinema.
Agree with
@levimax, you want bigger drivers that manage 20 Hz or below with authority.
But I add that this dependes on your room size, you listening levels (3000 micro R|evolution give 84 dB at 20 Hz) and your sensitivity for low frequencies. Usual human threshold at 20 Hz is 78 dB SPL
SVS 2000 will fit better a medium or even Big room if you have 2 units.
BTW, I will probably buy the 3000 micro R|e, my room is little size and I only use my setup for music: this is the targeted public for SVS with micro lineup.
POST EDITED: and of course, never use subwoofers without DSP control, the integration with monitors at crossover frequencies is crucial, as well as smoothing room modes.