Another idea, why not try and convince your dealer to let you try both and promise you will not return both?
Then you can find out if AARC really could make a better difference for you. In my opinion, Audyssey (using the App to adjust to you taste or to at least customize the curve the AARC's) and AARC will produce a difference visually on the screen, but no one can hear a difference when watching an Atmos or Auro3D movie, let alone hearing a preferred "sound quality". It's just not going to happen in a controlled DBT or even SBT.
From what I can see, DL may have an edge in theory, but I don't see the same for AARC at all. Why would it do any better, and last I checked (could be wrong) it is still PEQ based only. The main appeal (to me..) has been the PC based interface so there are much more flexibility for those who like to play, but with the availability of the MultEQ Editor App and Ratbuddyssey, I no longer consider the PC based UI an advantage.
I know each has their followers (or fanboys, to be more precise..), but show me something based on studies such as those conducted by Harman years ago, or at least hard evidence on paper. I spent hours searching for such evidence and found only anecdotal subjective reviews without hard evidence, or with limited REW (or similar) graphs presented by self proclaimed experts.
Just ask
@AcuDefTechGuy about Room EQ, I think half the time he may not even bother using any!! Or ask Dr. Toole and Dr. Sean. And I have been around AH long enough to know ADTG is the only one, for example, the respected TLSGuy might not think a whole lot about any Room EQ, DL, AARC, Trinnov or whatever else. You can see why I am so skeptical about people's claims based on their subjective experience. Remember, they spent the extra $, so they are biased and have to justify the spending to themselves..
For sure DL, Audyssey and AARC will be effective in levelling and shaping to some extent the range from 20-300 Hz (or lower). Whether one can hear a difference when the same customized target curve is used or not is the question and I know the answer..
By the way, along the same idea that you now have, also consider the far more cost effective option of adding DL using the minidsp add on solution for either AVR. Yes there will be some extra wires you have to hide, but it will cost you a lot less than the Storm audio that is not even HDMI2.1/8K ready at this point (not a factor obviously if that doesn't bother you at all.
For the price of the Storm audio, I hope it will be trouble free for many years. Funny how people would think "separate" AVPs will be so much more reliable than AVRs aside from performing better because AVRs are jammed pack in one box. Just think about how many extra parts/circuitry are packed into the Stormaudio!! It is one thing to cry about a $2,000 unit when it fails, but $20,000? And for "better sound quality", really??