All of this can be handled with virtual copies/snapshots, export presets, and smart collections (i.e., existing tools). The virtual copies let you do variations. The snapshots/history let you do iterations (same style, but additional work based on client feedback). The export presets take care of the file formats, naming conventions, color spaces, image sizes, export locations, etc., so you don't have to worry about getting it wrong. You have the option of adding the exported image back to the catalog immediately, if you want to keep track of it. The smart collections make it possible for you to find images automatically, without your having to maintain them, as long as you have the criteria clearly defined.
Eric, there's a couple of essential problems in this.
1) LR can not do the variety of iterations that PS can. How about a variation with the cow in the shot and one without? Give me a pen tool, layers with adjustable masks and blend modes, a viable clone/healing solution, cut and paste, etc, and we can begin to compare, but not until.
2) There's no failsafe. You have to have an absolutely impeccable workflow, with no slipups, and no legacy files or it falls apart. What you are essentially saying is that if you are incredibly organized, not prone to errors and are a LR master, then, and only then, LR can help maintain what you already know to do.
The problem is, if you're not "there yet," or drop the ball from time to time, LR can't well be used to clean things up and "get there."
So rather than allowing the program to read basic characteristics of a PSD/TIF/JPEG, and sort, filter and smart collect along those lines (like Bridge can,) users are out in the cold and need to come into LR as advanced users with their PSD/TIF/JPEGs already sorted, maintained, encoded and organized.
If you have a couple of concrete workflow examples to describe, perhaps we can drill down and figure out exactly how to set up the various tools in LR to carry them out.
I would like to address this but I think it's best as a separate thread.