lightroom is awesome because its a workflow tool with some editing capabilities. CS5 is a pure photo manipulation tool with no workflow capabilities, and has to be used together with Bridge.
i use LR 99% of the time now. haven't fired up CS5 in more than a year.
you need to spend some time to understand the preferences and settings in LR to get it to work the way you want. i have my files in my own windows file folders, and just import them into the LR catalogue without moving. If LR is somehow discontinued or becomes to expensive, i still have my raw files and xmp sidecar files that can be used in any photo workflow or editing tool.
i like how you can quickly use LR to export multiple formats as and when you need them, instead of doing all your edits in CS5, then having to save and export to jpg/tif/dng to save the edits.