As my personal experience, friend at one agency was issued an early X-Drive, and it might be even worse than Marnie's ImageTank... Abysmally slow and small battery.
Bear in mind that the "autonomy" figures on that website are unclear about verification. Some devices offer verification which reads the card two times, comparing the data. Which may or may not halve the times mentioned there (the website is mostly compilation of others experiences, so not truly a test of all devices!)... Good light! fra