Originally Posted by
lineinthewater
I've talked with my LBS employees ad naseum about my preference for SPD, both for pedal engagement and walkability. They are very polite and they try not to make me feel like the oddball out, but they are simply stuck in their mold that road shoes, road cleats, and road pedals should only be used on road bikes.
As others have mentioned, I've passed many many road "purists" in their "more efficient" setups. I'd like to see exactly what the power advantage is with road pedals/shoes - some hard data. With my carbon-soled MTB shoes, I don't see the argument.
Probably more about weight and stiffness than SPD vs SPD SL. Pure competition road shoes are a few hundred grams lighter and a bit stiffer than the best SPD combination. But really only make sense for competition. No competition level Shimano road shoe will take SPD cleats.
You might want to ask your LBS guys about Shimano Pontoon Adapters - they're a specific adaptor (SM-SH40) for using SPD cleats with road shoes with smooth outsoles such as is usually found on Sport, and some Triathlon and Multisport shoes. Some shoes will obviously take either SPD or SPD SL systems, some will take only one or the other.