Question about Shimano LX M-561 black cantilever brakes

[bruno_h2]

Hi to everyone... I have a question about the LX cantilever brake series (the black ones) and the SLR plus levers... I have an set of M-561 brakes with the arms slightly longer than the M-560 series, some people calls them as medium profile models... I'd like to know if they offers more brake power than the short ones and if it's best to matching them with the M-564 SLR plus levers instead of the normal ones to achieve more power from the brakes?? thanks in advance!!!