The 8351 with a sub (preferably 7382) is on par with many big speakers. GLM (Genelec’s DSP) makes sub integration child’s play. How big is your rom? Listening distance?
The room is roughly 3m x 5m, that's a bit inaccurate though because one side opens up directly into the kitchen which increases the volume of the space by probably +50%. Right now I have speakers in front of one of the long walls, so listening distance is ~2.25m. The 7382 looks... a bit too serious for this space, haha. So I'd probably want to do something like 2x 7370.
I'm not in any particular rush to buy new gear, and as I mentioned in another thread I'm probably going to try a (relatively) cost effective multi-channel setup. It would be cost prohibitive with 8351s for me, which is why I'm curious about the Kali IN-8s. I may also end up moving pretty soon, and might have more space. So I'm probably just going to wait and see, get a proper measuring mic and take some measurements of the performance of my current setups and then decide what to do later this year.