Full Range comparison

I would look at the Mark Audio paper composite full range drivers (such as the Alpair 12P, which I think is their best driver).  They are excellent, sound very natural and have a very flat response.  The gold/grey metal Mark Audio are nice too, but tend to have a bright edge to the sound due to the breakup distortion of the metal cones.

I do not have direct experience with the Seas full range drivers, but they all tend to have upper frequency spikes and increases in sound that need to be addressed with crossover notch filters and such.  Also, full range drivers that have the wizzer cone in the middle tend to have horn-type signature (can be slightly shouty and have a slight echo in the high frequencies).  With a properly applied notch filter, these may be really nice.  Seas makes excellent drivers and have strong magnetic motors, but I would probably not choose them because of the wizzer cone.

The Seas Exotic will play lower in the bass due to their lower free air resonance, but will have spiky and wacky response above 2KHz, like many other woofers do.  The Seas Exotic will also take more power and have a larger maximum excursion.

The Mark Audio are very flat and can be implemented without any special crossover notch filters or anything (just connect wire directly between speaker and binding posts.  It's extremely hard to design and make a full range driver that does everything right.  It depends on what area is important to you.

This is the kind of testimony i am looking for, as i have no experience with FR, only know that FR's have *some issues*. 
No I really did not want a  xover, and the Exotics are a  bit out my price range at $700'ea USA dealer, but I can get them at $500/swedish dealer. 
I will now take a  close look at the Mark Audio  Fr you mention. 
The amp layout, late next yr, is taking most of this 2nd system budget. I already havea  Jadis Defy 7 + about to add a cayin SC6 tube pre, and will upgrade my SEAS Thors with Mundorf silver oil along with 2 massive Gold Silver i bought off ebay,,madisound will build new xovers employing all  new parts, so my 2020 budget is about blown on that project + I plan to upgrade caps in the cayin and jadis. ...in fact,,i may have to push the 845/FR dream 2nd system off to 2021. 
I'm  in research mode right now. 
Thanks for this important testimoney to help in the decision.
...

I have no knowledge of the brands you mention, but do have first hand experience with another maker of full range speakers.  You owe it to yourself to look at Omega Speaker Systems, designed and hand-built in Connecticut.   https://omegaloudspeakers.com/

Omega has a full range of monitors and floor standers.  I have been a very satisfied 4+ year owner of a pair of their Super Alnico Monitors which employ a 6-inch full range driver.  I also listen to classical chamber/voice/ and orchestra, and can only say these speakers are amazing.

If you're interested, watch this:

https://www.youtube.com/watch?v=30H7t6ENTtI

It's the first in a series of videos where Mark Fenlon (MarkAudio) talks about the design of his full range drivers.  There are 6 parts (6 videos) total in this lecture.

~~~~I;m back~~~ In 5 minutes~~~, Not sure how i missed these Mark Audio on madisound, as i looked over nearly everything FR on Madisound,,,,carefully,,,or was it a case of tunnel vision, as i am  a huge fan of SEAS only, and could not consider anything other than. 
The Mark Audio Alpair 12P8 is really interesting, and this will be my choice, and the clincher here is, well affordable, making ~~The 2nd Dream System~~~ a  closer reality. 
 
As soon as i dump my cayin MT and chinese pre, both at a  50%+ loss, i will regroup and get the Mark Audio 8 inch,,,play around with that on my jadis Defy. I see the MA is rated 90 db,,not too efficient fora  FR. But if as you say,,all the funny things with whizzers and break up is not there with the MA, this will mean no xover, just straight muisc. 
I mean, we have cd players/pre/amps,,,then xover in a FR???  The FQ;'s are being pulverized to a  mush. 
I may end of liking the FR over the SEAS Thors...will bea  good shootout. 
Thanks for your suggestion, would have certainly overlooked this fantastic looking Mark Audio 8. 
No I do not plan to push the vol of the Defy, nor do i listen to harsh rock. 
This will get very interesting,,hopefully YT has some vids on this MA 8.
Thanks
paul