The graco is a nice little machine but i think its too prone to blocking with multi, you would need some sort of filter on the hopper. The pre bagged plasters that are allready mixed are the niche for this machine. You can buy the PBP and spray them straight on the wall without the need for uni bond or bond it. Overskims can become a niche market quite quickly because you will do them faster and cheaper than a traditional overskim system, any left over can be pumped back into a tub with a lid and placed in storage.
The graco will also spray a texture finish with PBP that is seen all over europe and could be mistaken for woodchip paper. You can also spray texture finishes outside like pre mixed bucket coats, this is ideal for a tart up on some houses.
The PFT Ritmo is better for skim because you only drop the bag in and it gets mixed and conveyed to the wall and sprayed on. Plus it can do a whole lot more