Full disclosure I am with the house but have had the opportunity to listen with the 4.4 Bal and 3.5 Single ended on both now (and IE 600), and enjoy it very much. It's not my full-time configuration for these earphones as I most often pair with a SE source (Dragonfly Red), but appreciate the balanced option's extra nudge of depth and nuance. I do so much switching between Sennheiser headphones that 3.5 is my common denominator, but when the occasion calls, 4.4 rocks.
For me, the analogy that comes to mind is that of taking the 1st sip of a freshly opened ice cold Pepsi (or beer or bite from a bag of chips or spoonful of ice cream, etc) vs the 2nd sip.
By the time you get to the balanced vs unbalanced part of the equation, you've hopefully managed other variables like source and sample rate/bit depth, etc, as you're looking to have a more critical look backwards into the audio tunnel. The sum of all of those
other improvements makes going balanced more enjoyable and rewarding. Just my 0.02 cryptos.