Hi folks,
Just thought that this thread was loosely enough based on a couple of our products that I could use it for a shameless plug

.
We, Malladin's Gate Press, have our own product which uses 10 level core classes. The product is DarkLore, a dark fantasy campaign setting and general toolkit for low magic, dark, heroic fantasy. This product has recieved fantastic reviews here at ENWorld and has even been nominated for a Gamewyrd award.
The approach we have taken is thus: To attempt to take the benefits from D20 Modern and convert them into a suitable format for Fantasy games. D20 Modern is more deadly and character progression is operhaps slower, but with plenty of variety and flexibility on achieving your character concepts. Hence we replaced the D20 Modern core classes with 6 classes, each loosely based on an ability score and more suited to fantasy gaming. The classes are: Warrior (Str), Thief (Dex), Outlander (Con), Scholar (Int), Devout (Wis) and Destined (Cha). We then basically took apart each of the 3.5 base classes features and made the not-too-powerful ones into talent trees. Genrally I think the character system is one of the best bits of DarkLore, and we have recieved a lot of praise for it (slighly embarrassed but proud smile).
We're also planning on taking the same approach with Etherscope, our forthcoming game setting.
I think that the 10 level approach has to be tied to free multiclassing. Players can then create whatever character concepts they like. IMO this is a good thing.
Cheerio,
Ben
www.malladinsgate.com