I have a ZD-985 and, yes, you can solder with it. However, there are a couple of considerations.....
1. (-ve) The geometry of the tip. The supplied tips have a hole up the middle and are not shaped with any sort of useful profile for applying heat in many soldering situations. (If you can get regular tip shapes that would fit, then this won't be an issue - as long as they are decent tips.)
2. (-ve) Handpieces tend to be more bulky than straight irons. This, plus where the handle is built like a pistol grip (so you can activate the vacuum pump), means controlling the angle and movement of the tip will be more challenging.
3. (+ve) They tend to have decent heating power (to deal with the cooling effect of the vacuum), so if you can get good thermal contact with the workpiece, they can help in soldering heat sucking jobs.
There may be other points, but I haven't tried using mine "in anger" in this way.