The question isn't whether balanced is better than single-ended in general, it's whether the Desktop Max is better than the Desktop Balanced. Virtually everyone agrees that balanced audio is at least technically better than single-ended, but make no mistake, there is absolutely nothing close to a consensus on how large (if any) of an improvement there is.
If you have a balanced source, it might be worth getting the balanced amp to take full advantage of what your source can provide. On the other hand, if your source is single-ended getting a balanced amp would be needless expenditure.
Also, don't forget about the need for a balanced headphone cable, which run anywhere from $100 on up.
Personally I'd opt for the Max, because it's a higher quality amplifier, and I'd be willing to bet that the improvements you'd get from the superior components outweigh the improvements you'd get from a balanced setup with inferior components.
One thing to note about balanced is that it's louder, which can mess up perceived differences between it and single-ended.
If you want to be "safe" you can get the Max, and if it really doesn't satisfy you, you can return it and go balanced.
I've been struggling with the "go balanced" question myself, but ultimately decided to invest $500 in upgrading my WA4, and remain on the single-ended path.