Hi FF:
No need to worry about file Degradation converting back and forth to/from LAB in
PS. Just be certain the use Image>Mode>Convert to Profile command and select LAB, CMYK, sRGB or whatever, from the listing. Many studies have proven that the conversion is lossless, having converted back and forth thousands of times in the testing. A good primer onLAB is "Photoshop LAB Color: The Canyon Conundrum and Other Adventures in the Most Powerful Colorspace" by Dan Margulis $20 at Amazon.com.
So far as workflow from RAW, I would set the software preferences, in whichever is your program choice, to do a minimum of enhancement and adjustment and depend upon your own post processing skills to yield the desired results. Control is everything and this workflow will allow you the most flexibility.
Just one man's opinion.
Stosh