Can't comment on spotify but I actually came from the X3 2nd gen and still have both actually, although I'll probably be getting rid of it soon unless something changed with the X5. To me, the X5 3rd gen is way more detailed and musical. The X3 2nd gen felt too bright when I first came to it from the X1 1st gen, but has considerably tamed although I think the treble area is still a bit rough. That said, the X3 2nd gen isn't really a big improvement if you have a recent phone sound quality wise, but the X5 is considerably better on that front. Again, operation has been smooth and I haven't encountered any major issues or lags/crashes but I also have really only installed poweramp and neutron on it and have spent most of my listening on the pure music mode. As you may have saw, the last update released recently had a little bug but I think Fiio did a good job in patching it out in a short period of time. I had the same worries as you in regards to the stability of this DAP especially as the X3 2nd gen had also been shaky at the start but I think both DAPs have reached a point where it is stable and most issues that can be taken care of has already been taken care of. I would not say that the X5 3rd gen is inferior to the X3 2nd gen in usability/performance either aside from maybe the lack of hibernate/low power sleep mode, but battery consumption thus far has been much better than what I was expecting.