I'm a long time Orbot user and I can tell you that the weight kit makes a big difference when cleaning a variety of surfaces, including carpet. In days gone by the weight kit had individual plates. You could adjust the number of plates depending on condition and floor type. For example, you'd almost always want to run two plates per side on residential (*gasp*). Tile and grout would typically be three per side. I believe HOS changed this to one combined weight/plate, but I'm not entirely sure.
Mikey, you mentioned the machine not being able to support a brush. This would be running the brush on carpet only, correct? If so, that may be the case. However, I can tell you that the tile and grout brush for the Orbot is great and jiggle-wiggles the grout clean. The bristles are cut just right.
Like the others above, I too have a Mytee as well. It's been solid so far. It and the Orbot seem to perform similarly.
Finally, let me say that this is a great time for low moisture and dual method cleaners. Never before have there been so many options with competitive pricing. Between the Vibe, Mytee, Vario, Cimex, Liberty and Champ you can find a machine that suits your wants and budget.
The weight kits are for hard surface was my understanding.
We'll get to the bottom of this at MF
Vibe vs Vario shootout!