The way these things normally work is that you're only allowed to use the name and marks if you're an official licensee.
So if you put the USB logo on your marketing and claim to have a "USB Mini" connector in your specifications then you could be in trouble on two fronts: (1) the usb folks can sue you for using their IP and (2) purchasers can claim the product is not "as described" which may given them certain rights dependent upon the location.
Not using the official logo shouldn't be a problem in hobby market. Everyone will recognise the connector. Not being allowed to identify it as USB2 or USB3 or whatever, that could be a problem. I'm sure there are creative ways around it though.
So if you put the USB logo on your marketing and claim to have a "USB Mini" connector in your specifications then you could be in trouble on two fronts: (1) the usb folks can sue you for using their IP and (2) purchasers can claim the product is not "as described" which may given them certain rights dependent upon the location.
Not using the official logo shouldn't be a problem in hobby market. Everyone will recognise the connector. Not being allowed to identify it as USB2 or USB3 or whatever, that could be a problem. I'm sure there are creative ways around it though.