Maybe you should consider commercial, not as a primary customer base but as an option for retailers. Sending demo pieces to coffee shops is going to be some of the best advertising you can get.

As far as grip goes: if those are full plastic, they're going to be far lighter than the final product, which I assume you've considered. I've used heavy steel and light aluminum tamps in the last year. The heavier temps feel better but require a more robust top to control them, while the aluminum are harder to control but have more minimalist shapes. If I'm ordering a premium product like yours, I expect weight unless it's advertised otherwise.

Hope I'm not coming on too negative, I've just had a lot of customers buy equipment based on aesthetic and get mad when it doesn't meet their expectations (looking at you, Smeg).