I would look at the Commander X8 and the Commander X16 like the Vic 20 and the Commodore 64. I like the idea of both. I am not opposed to kit versions and would more likely consider one as I understand the time and cost associated with populating the board.
I think I like the two different products for different reasons - the X8 is ready to go, has USB, and as you mention the sound capabilities are more than enough. I liked the dual sound chips in the X16 as I was always interested in music production with it.
Now I do wonder if it is a possibility to release a case design so that if people were to choose to they could 3D print or make one of their own, or find an off the shelf case that works and slap fancy sticker on it. I think the lack of case is a bummer but not a deal breaker, especially if it gets the computer in people's hands today. And while it may not be much it may be able to infuse some cash into the continuation of the project.
I don't think the X8 dilutes the brand. I personally think it builds on it. I am unfamiliar with the feasibility of it but in the end would it be possible to make the X8 compatible with the X16 end product?