In the absence of comments from any SF owners at all, I’ll try to be helpful.
I don’t have SFs, but do have an Atom in my bedroom. I use Shahinian Compass speakers, but we also heard it with my girlfriend’s Neat Iota Alphas before they went off to be powered by her Naim Nova.
None of the one-box players are the last word in detail retrieval or max volume in a big room. To me, what they do really well is present music with good detail, openness and accuracy - while concentrating on making it easy to hear what is going on and hard to stop foot-tapping/ head-nodding/ smiling.
From the numbers and other SF speakers, I’d expect the Lumia IIIs to give you a much sweeter and more airy presentation on female vocals. They would doubtless work even better with something with much more grip and power than an Atom, but I don’t see why the combination won’t work well.
There are other speakers to consider of course, including similar stand-mounts from KEF LS50 or R3 and Wharfedale Lintons to JBL409s, plus literally dozens of others. Before spending that sort of money, I would encourage you to hear 2 or 3 options at least - ideally in your home, but definitely through an Atom like yours.
As a final thought, you could look at small floor-standers too, not least because many give more bass (perhaps removing completely the need for the sub, depending on your room).
If you can, I’d encourage you to hear Neat Iota Alphas, which are 45cm high and happy to be 20cm or so from a rear wall - not because they go ultra-deep but because imho there is nothing that combines detail and musical involvement so well for anything like that money.
Other small and slim floor-standers of a more conventional height (B&W and Tannoy being typical UK examples) will have deeper bass (and are more likely to make the sub redundant), but they take up more space.
Good luck! Do tell us what you buy and how it goes.