kevtn8, I have thought of replying to your question but have delayed. I have written about all you ask many times in the past and I'm not sure why I haven't been able to bring myself to do it again. I suggest doing a search with Omega or Omega Alinco as keywords to find more detailed comparisons I've done in the past.
I have...
1) Omega Super 7XRS with the 7RSA driver with Alinco magnet which is no longer offered. These are ported to the back.
2) Omega Alinco Super 6XRS with the top of the line Alinco Driver that is different than the above driver and can be viewed on Omega's site. This driver has not changed to my knowledge since it's introduction, so any used pair would have this superior driver. My pair were made in Dec 2011. They have downward firing ports that, to my ears, provide better bass response than the above speakers.
3) Decware/Turning Point Audio HR-1s are in my main system with a Torii MK IV, CSP3, ZP3, Rega RP6 TT with Exact 2 Cart, Jolida 100 CD Player and the cherry on top is an Omega Deep Hemp Sub-woofer. The HR-1s will remain there. I spin Vinyl about 99% of the time there...in the "Cave".
4) Zu Audio Soul MK II speakers that have a coaxial mounted tweeter with a high pass filter...no crossover. I'm no techie so I'm not sure how a filter differs from a capacitor as found in the HR-1s.
I currently have the Omega Super 7XRS and Zu Souls side by side in my second system which includes a pair of 2.3 WPC Zen Signature Mono Blocks that were manufactured in 2008 and then modified several times by the original owner. My source is a Jolida 100 tubed CD Player. I have speaker cables with bananas so it takes less than a minute to switch from one pair of speakers to the other. As I have said in the past, I find myself almost exclusively listening to the Souls and can't remember the last time I used the Omegas. I have not tried the Omega Alinco 6XRSs there. I will eventually but I'm confident the outcome would be the same. This quote from an earlier post of mine sums it up..."I have used Omega speakers with Alinco drivers with both Amps ...they do well with the caveat that they have a forward top end that is emphasized with both Omega speaker pairs I own. I can roll input or output tubes to moderate this effect but not completely to my satisfaction. I think most people prefer this kind of sound hence the popularity of Omega speakers with Decware Amp owners."
I find the Zu Souls to have gobs of detail, tone, transparency, etc...without emphasizing the top end like the Omegas. I also feel the bass is more satisfying with the Souls. The Omegas with the bottom firing ports would probably be close to the Souls in Bass performance. My second system does not have a Sub as my primary system does. I listen to Jazz mainly...lots of piano trio...Keith Jarrett and Bill Evans...and can tell you I find the Bass and Drums/Cymbals just right with the Souls where as with the Omegas both fall a little short...a bit too much high end and not quite enough low end. Of course these observations are only one man's opinion. Others may and do prefer Omegas over Zu Audio speakers. I believe there are far more Omega owners than Zu speaker owners here, thus my original post to encourage Zu owners to speak out. I hope this helps. Mark.
PS...as to the difference in efficiency...99 vs 93. The small Zen at 2.3 WPC provides adequate power for the Omega Alincos but do so with less headroom...ie. I have to turn the volume knob quite a bit further to get comparable volume. With a higher WPC amp like the 25 WPC Torii, the difference would be less noticeable.
PSS...I might add that without getting a pair of Souls into your listening room you will never really know if you like them. Zu Audio has the best trial and return policy in the Business. The trial is 60 days (that can be extended to 90 days upon a reasonable request), if after 45 days...not before...you don't want them and paid shipping on your original order, they will arrange to have them picked up at your house with no shipping or restocking fee provided they are a stock pair...not a custom order. These speakers need an adequate break in period to show their true colors hence the exceptionally long trial offered. I know of no other speaker manufacturer that can match this policy. This goes for any speaker bought from their website...pre-loved or new...as well as any speakers bought from other channels like ebay. Read the policy below and ask questions. There are three guys who answer the phone and they are all very helpful, one being the CEO/President/Founder, Sean Casey, who one day answered my call. It wasn't until after the conversation when reading their site, that I realized I'd been talking to the head guy. Customer service is great!
PSSS...I'll also add that when the Souls were introduced and until not long ago, they retailed for $3500...now $2000. I really don't care what speakers people buy but I remember how hard it was to figure out what to purchase. The reality for me was even after reading all the reviews and other's descriptions/impressions, I still didn't know until I lived with them for a while in my own system, which speakers I liked best. Everyone's "Ears" (Preferences), Gear and Rooms are different so anything less than listening for yourself is a crap shoot. Again my opinion.
http://www.zuaudio.com/60-day-guarantee