Have you tried a factory reset on your DX90? It might solve the scan card problem.
As for missing the last two seconds of songs, have you turned gapless mode ON? And does it still occur even after gapless is ON?
About the battery life, it's true that the X5 last at least 3-4 hours longer, but the upside is that the DX90 will be more environmental friendly in the long run since the battery is user replaceable. This also means that with several fully pre-charged spare batteries, you can just swap the currently flat battery in the DX90 with a new fully charged one and you're ready to continue enjoying your music without having to put it aside for charging.
Just my two cents.
Tried a reset via settings menu yesterday, no difference with screen appearing. All songs are seen ok.
The two second at end missing shows on counter and has been a problem for many since DX50 apparently and still continues. Yes, gapless on.