I just finished a journey to select a new set of speakers, and my tastes landed squarely with Sonus Faber. I will try to convey my experience in what my ears, heart, and wallet experienced in that journey. This may be a bit long-winded, but hopefully it provides some insight into my navigation of a very similar question.
To start, I had a set of Martin Logan electrostats that I've always loved for their clarity and depth, but needed something with a wider dispersion and just simply worked better in the dual roles of 2-channel plus light home theater use in my living room. Initially I had gravitated toward Focal Maestro Utopias which are, of course, phenomenal speakers. However, I walked into my local SF dealer store and heard a set of speakers that brought me true joy: a set of Olympica Nova Vs.
The sound just had a special something that truly had me smiling ear-to-ear as I listened to many of my favorite songs. Steely Dan, Norah Jones, Art Pepper, Home Free, CSO playing Mahler 5 - all of these artists I have heard on dozens of speakers including stuff way above my means, but this was truly the first experience that truly connected me to the music. The highs were nearly as clear as my electrostats. The mids had a warmth and depth that allowed me to melt into the music. The bass was punchy, controlled, and extremely musical. The staging was wide, deep, and believable. These were everything I ever wanted in a speaker, and at a price point that was actually below those used Focals I mentioned.
The salesman had me come and listen to the Amati G5s they had set up in their listening room, and I listened to many of the same songs that had so captured my ears and heart on the Olympica Nova Vs. The result was a two-fold conclusion: a) Amatis had an even better mid/high range than the Olympicas - cleaner, clearer, sweeter, even more musical; and b) they lower end was tubby, flubby, loose, and the opposite of musical. There was something even more magical in that mid/high range that made me fall even more in love with the sound, but that low end: yuck.
What to do?
After much deliberation and discussion with other folks whose opinions I trust, I concluded that the Serafino G2s plus a couple of subwoofers would give me everything that I wanted. The Serafinos have the same midrange and tweeter as the Amati G5s, but with 180mm woofers similar to the Olympicas instead of the 220mm woofers. In my mind, the smaller woofers would be more easily controlled, and two 12" JLAudio E-subs would more than make up for the difference on the low end. The Serafinos are also easier to drive, meaning I didn't need to upgrade away from my beloved Goldmund SR150 amp @ 200w/4ohms. Your Luxman @ 220w/4ohms would have no trouble with the Serafinos.
I have been living with this setup now for about two weeks. While they aren't even fully broken in, I can confirm that my intuition seems quite correct on the sound profile and performance. The mid/highs are even better than what I heard in the Olympica Nova Vs, and the bass is punchy, but controlled and musical. These are truly turning out to be my "forever" speakers, and have that special something that I just didn't hear in any other speaker I auditioned.
So to your question of "is it worth upgrading" to the Serafinos: that's as complex a question as any. In my scenario, if I didn't have the benefit of the dual 12" subs (which I'd honestly recommend for any system, but I digress...), I think I might actually prefer that third woofer of the Olympicas over the Serafino's two. It really does add a lot of air movement and performance. However, the tipping point for me was that upper end. There's just something even more "Sonus Faber" about Homage line's upper range performance over the Olympica Nova. The Olympicas made me first fall in love with that sound, and the Homage made me actually pull the trigger.
My bottom line: The Serafinos + subs cost me a good bit more than the Olympica Nova Vs, but they were absolutely the right decision for my "end game" speakers. My ear-to-ear smile and warm every time I listen to these speakers make me truly thankful I had the means and opportunity to experience them.