I own a Spelling Bee Deluxe (which allows you to show the board empty before you begin putting alphabet cards into it).
I bought it when I was still doing Kids' Shows, and therefor didn't mind how "magic prop"-y it looked at the time. However, the same appearance prevented me from using it in adult-attended shows.
I think it's otherwise a nice effect with a clever methodology (at least in the Deluxe edition), but it would be nice if someone came out with a more "professional"-looking version for corporate work.
It still wouldn't be pure "mentalism," but rather "mental magic" (along with the Mental Epic).