I've seen a plugin that adds layers to LR which would save a lot of to-ing and fro-ing to Photoshop. The plugin is actually stand-alon, but also integrates with LR to some extent. It allows many of the layer options found in Photoshop. Not tried it but seems like a cracking idea! 🙂
Making LR more of an editor could make Photoshop redundant for pure photographic work