Exporting edited ('current') photos at maximum quality?

Question

I currently use iPhoto 9.5.1 (on OSX 10.9.1) to organize my photos and I use an external editor (Photoshop) to edit them.
When I get an image that I want to then use for something I take it out from the iPhoto library. Previously I did this with a simple drag and drop, but that functionality mysteriously and suddenly ceased. Now I use export current. (I don't want the orignal verison that has none of the photoshop work)
From what I understand, exporting the current photo exports the version from the preview folder.
Is this a full quality version that is exactly what I created in photoshop and saved? Compared to the file in the masters folder would it be the same quality?
In other words is there any loss in quality along this path and if so where does it occur (or is this not the path)?
Camera-> masters folder-> iphoto library -> external editor -> previews folder -> iphoto library -> export of current
I don't care so much about metadata and primarily care about the quality of the exported edited image. I use them for other purposes where metadata is irrelevant (like parts of a design or printing).

Answer 1

Thank you,
The question I have is in that tip you specifically mention that selecting 'current' as kind of export would export "the iPhoto Preview, a medium quality jpeg, it won't have all the metadata."
I did some tests with a tiff, png and jpeg file and found that this was not the case. The tif exported a tif, the png export a png and the jpeg export something closer to the original jpeg size (not anywhere near medium quality). Here are the results of the jpeg test:
The one discrepancy I notice is that there is a 200 byte difference between the version saved from the external editor and the version exported as current. That is minor, but I'm wondering where that may come from. Is it a result of saving the file with photoshop or is it something iPhoto does to the file?
The discrepancy seems to be greater (up to 29kb) with the png test:
And I think the discrepacny is likely from what the external editor does in saving the file and not what iPhoto does. Here are the results from my tiff test:
The inclusion of the color profile in the save from the external editor brings it closer to the size of modifed version.
So I find my concern that exporting 'current' would severely reduce the quality by always making a "medium quality jpeg" is not the case, and that it does export something very similar to the work I did in the external editor.
(I like using iPhoto for how it organizes with metadata. I just don't need the metadata for files/images that I export from iPhoto. They move on to a different purpose where such data is irrelevant. Also I'm curious if iPhoto is not meant to be used for organizing media what is it's primary purpose?)