#1 – primarily, very few will have the skill, tools, and patience to get this mounted correctly (more on this below).
#2 – No support, no instructions, no mounting template, no mounting hardware.
#3 – Seems flimsy. Mounts with (user-supplied) 6x30 bolts – so a lot of force relying on a thin, long bolt. Telescoping handle has a lot of flex to it, doesn’t really instill confidence for a long life.
More on mounting issues: granted every installation will be slightly different depending on the cabinet and the user’s needs. However, the two brackets that are permanently bolted to the cabinet must be, in all cases, carefully aligned for the trolley to attach properly. It is extremely difficult to insure proper orientation and spacing for these two brackets. The tolerance for error here is quite small, approximately +/- 3mm. The obvious solution would be to have a single mounting apparatus that would ensure the trolley-brackets are both parallel and the correct distance – this way, even if the mount is crooked, the trolley would still attach.
I noticed another reviewer said to ‘lay the assembly (trolley with two brackets) on the cabinet and mark.’ Unfortunately, the trolley blocks access to 5 of the 6 the bolt holes, so you can’t mark their location accurately. The brackets are irregular and access is limited, so it isn’t possible to get any kind of marker into position while the trolley was there. (I think this technique might work on a home-made cabinet, before assembling the box, but on a store bought cabinet it will not.)
You also need to determine the correct placement of the bottom bracket so that the wheels have appropriate clearance; again, I was fairly surprised that the manufacturer gave no guidance for this.
This detachable trolley is really interesting idea, and I hope they make it useable soon. In the meantime, I’m going back to my hand-truck and bungee cords.