I finally got to try the X-ADV last week. Like the curate's egg, it is good in parts. It has bits that are better than the TMAX and bits not so good.
The good bits...
Performance. Way faster than the TMAX, both in acceleration and top speed. Easier on a dual carriageway when overtaking and nippier in town.
DCT is better, in my opinion, than CVT. Quicker to respond from a standstill and on the move.
Looks. Subjective. Eye of the beholder and all that, but it's funky.
Riding position. Higher handlebars suit me better, but they are very wide.
The bad bits...
Comfort. The TMAX is way more comfortable.
The dash. Superb on the Yamaha, acceptable on the Honda
Electric screen on the TMAX beats the manual on on the X-ADV
Idiot switchgear on the Honda. Why swap horn and indicators when all other bikes have them in a standard position, as did Honda until recently.
Would I buy either? Well, I didn't. I bought a Triumph Tiger Sport 800 Tour instead. I didn't like either scooter enough to part with my hard earned cash, whereas the Triumph lit my fire immediately.