Significantly is subjective so I can not answer that one. But technically the QS is a big step up from the Fireface. Both the analog circuitries and the AD/DA converters are superior to that of the FF.

It is..
running quad Martin Logan Electrostatic Sequel II loudspeakers as FL,FR,SL,SR channels, and two added electrodynamic speakers from LINN (KOMPONENT series) as centre channels (CeL, CeR), all passive as being powered by individual amplifier units
this setup allows me to operate the centre speakers with its dedicated subwoofer (that you can see underneath the gear rack) for basic stereo use, hence the entire layout for multichannel (5.0) or even better enhanced stereo in operating two L,R clusters of three speakers each...
All routing figures, output balance levels and the overall loudness volume is performed thanks to the versatile RME workbench , high quality and smart features easy to configure  at a glance
Basically I am using six channels of the QS for recording / playback of multichannel material as explained above, while the two remainding ones are assigned for recording those of analogue type equipment, tape recorder and turntable, tuner..
In the digital domain, Digirecorder is THE ONE for such issues, while Totalmix the friendly router for any I/O combinations
Additionaly to this, perfect realtime speakers matching equalisation is performed running Algorithmix LPPOrange extatic equalizer and the required task of phase / time array matching by Voxengo VST nice tools
I have to stop now, otherwise I could speak about RME, VST Hi-end Plugins, Saracon SRC, and Accuphase amplifiers for long long time...
I am now investing in equipment to record acoustical classical or theatre stages by myself, sound ...sound again and again, because I have now reached the right monitoring setup to experiment toward the top sound capturing technique using some personal setup...
The unusual mix of both professional and (reasonable) audiophile gears is what I suggest you to focus as soon as you can!

All the best