Cergorach said:
How compatible is it with OA and the D20 L5R line, mechanics wise?
The Legends books (the first being Legends of Excalibur and now Legends of the Samurai) use some new mechanics, but they are definitely compatible with the books you mention.
Samurai uses an Honor system in place of Alignment, but its pretty easy to convert the classes back to using alignment if you like that sacred cow. For the most part classes with an Honor requirement would convert to "any Lawful" while some of the PrCs like Otokodate, Yojimbo and Kensai would require a LG alignment as these are the "Paladins" of the system.
Samurai uses social class instead of race, with all the PCs being humans of various social castes. However this is easily ignored to be replaced with race, and there's some guidelines for using nonhuman races in the Campaign Guide as well.
Samurai uses spell points instead of spell slots, but maintains the 0-9 spell levels, meaning you can simply use the spell lists provided in the game and cast them with slots instead of points.
Samurai uses its own martial arts system, but since its feat based I think it should work pretty well with those presented on OA.
So there are a few differences, but having converted many adventures to run with Legends of the Samurai, it hasnt posed too much of a problem, in fact now that I've ran the system a few times I can do it on the fly.
Chuck