if that is only reason you think of upgrading I would hold until you have another reason or two.
Agree. I went from Yamaha to Denon, (YPAO to Audyssey). I have 2 subs and the dual sub EQ is nice. Audyssey did indeed set one a bit louder than the other. However, I'm not at all sure I could actually hear the difference.
And by the way, a simple sound meter is not expensive. Much less expensive than a new AVR. You could use it to check the balance of your subs, and other speakers, if you're interested. You don't need fancy software.
Your Yamaha will play a tone thru each speaker, one at a time. You simply sit in your chair and look at the sound level on your meter. Adjust the volume of each speaker up or down as you wish. The same for 2 subs. Simply connect only one, and look at the meter. Then connect only the other one and repeat. Your subs likely have a volume/gain control on the back. You can adjust them to balance as you wish.
In other words, I wouldn't trade AVRs only for XT32.