While the long end is a little faster that typical consumer zoom lens, it still needs good light or the ISO will have to be cranked up pretty high.

Generally larger is best for good light, while smaller is better in poor light

This often brings the lens close to the actual range of the object, especially if there is sufficient light

I was a bit concerned by the slow aperture (3.5 to 4.8) but in good light this proved not to be an issue.

Make sure you make both the speed and depth of field (ie aperture) have enough margin for error -- to do so, you must have enough light or

On an X-E2, with current firmware for both camera and lens, in all but the brightest light it hunts for focus and often fails, behaving like the poky 60mm macro and, like that troublesome lens, frequently failing to achieve focus at all

Generally larger is best for good light, while smaller is better in poor light

I hope the IQ stay top class, but looking at the pictures, I think that lens won't be compact/light neither.

AF on an XT1 is fast and accurate enough for most general shooting in decent lighting