The issue i see is that machines like this are already available, they have them over here called a dingo. Essentially a motorized shovel.
It would need to have some really fancy additions to make it stand out from brands taht have an established name to them. From what i have seen (never run one myself) is that they tend to be rather jumpy. As you move the steering levers, you move and it jerks, so for new users, it's rather jumpy. If you could address that, it could be an advantage.
The ones i have seen use a hydraulic pump to run the drive motors, not a piston pump like bobcats run. I'd like to think a vairable displacement piston pump would help with this and possibly make it more efficient?
The difference I see is those robot omni wheels. Have you built and tested these yet? They might be great or not, and they might be expensive to maintain and may not provide the traction that regular tracks or tires provide. And if they are actually better, then you'll have to show that pretty convincingly to woo customers. You'll need comparison videos and/or data in your marketing.
If you make the attachment mechanism anything different than the pretty much standardized quick-attach, then I believe most potential customers will view that as a negative rather than a positive whether it works better for whatever reason or not. You can currently rent or buy from various vendors lots of attachments that can fit those little machines. If you have any kind of proprietary mounting system, it will be more limiting than "improved" because of this. It's already a bit of a negative that those "mini skidsteers" use a smaller version of the quick attach that may not fit attachments a guy or business already owns.
Another difference is that you stand on the back step rather than standing on the ground behind it like the existing mini skidsteers. I don't know if that would be more pleasant to use or not, but off the top of my head I can imagine that you'll have to feel the motor vibration in your feet & legs the whole time you're using it and if it tips over, it's an increased safety hazard. So that's a difference that may or may not be viewed to be better.
As Tazza said, you'll need to really stand out to compete with the existing brands. I agree that if the existing offerings are jumpy because of the hydraulic system, then simply offering a hydrostatic piston drive, a very common thing even in lawnmowers, that should be a big improvement. First I would research mini skidsteers and verify that they indeed don't already have hydrostat versions - to me it seems very strange that they wouldn't already have models which are hydrostatically driven.
To compete with the existing market, you really need to be very knowledgeable about what exists in that existing market.