I use dual-sided pedals, but in reality I use the clipless side probably 99% of the time anyway. The Shimano MTB shoes are just fine for walking in. In fact, I've done many 20km hikes in them without any problems. It's worth remembering that MTB shoes are designed to support your feet when you're carrying an MTB over logs and other obstructions on MTB trails, so they're not likely to lose much to any other shoe in terms of walking functionality.