And yes, you can use the "Edit In" feature of Lightroom to open a rendered photo (in PSD, TIFF, etc format) right in Photoshop Elements Editor just like full Photoshop. When you save the photo and return to LR it's in the catalog as another version of the original, and you can even do LR editing on top of it (but opening it back in PS makes more sense to me). The nice thing is you can export, watermark, print etc the PSD/TIFF right from LR just like RAW/DNG files you've edited in LR natively. Very seamless.
A PS instructor at our University told us Elements was released as a light version optimized for photo editing, so what you mainly loose are some of the exotic design tools. I think LR 4 + PS Elements 10/11 is a killer combo.
This is what I do.
1. After saving in PS, LR shows two files of the same image.
2. The new TIFF (which I select to use) is labelled 1/2 and the existing CR2 file is labelled 2/2.
3. I immediately flag the CR2 file (2/2) and hide it under under the new TIFF (1/2).
4. At export I "Select Flagged Photos"
5. Then I "Invert Selection" which deselects all the flagged photos and selects all the un-flagged photos
LR does not export the flagged photos. It may not be the best way to do that but I only edit about 10% of the images in PS so it is easier to flag those as I work on them rather than flagging the other 90% for export.
LR used to have a "Select All Un-Flagged Photos" command but must have removed it during an update. Unless I have lost my mind and just can't find it.