Copper L vs M

My quest for knowledge continues...
In the process of completely rerouting and replacing my water lines a question continues to plague my mind (@#&! the voices!) Should I have used L instead of M? How many thousandths of an inch difference is there between the three schedules of copper pipe? If the water is going to eat through M, does using L or even K make a difference? My water is a municipal source and has a pH of 7.8 and a total chlorine of up to 2 ppm, so the typical problems associated with well water is not an issue. My thoughts tell me proper grounding and the use of dielectric unions when dissimilar metals would make contact are the most important factors to look for. I can't find any suggestions per the IRC or UPC unless it's in regards to above or below ground application.
Also, my incoming water line is galvanized steel (I wonder how much longer that's going to last if it doesn't choke off my water supply first) does the water meter act as a proper union?
Speaketh your divine knowledge o' plumbers of renown.

If you click on the "Replacing Pipes" link on the Terry's home page, your question is addressed.

Thanks Gary,
Found this link through Terry's page on Replacing Pipes:

http://www.copper.org/resources/pub_list/pdf/copper_tube_handbook.pdf

It is THE Copper Bible!

Sure is! This is a bit too technical for me, I just wanted you to see that Type L is standard for interior household plumbing given the Ph is within defined limits, which yours is.

copper

In any given area, "L", or "M" could be the "standard" for above ground inside the house water pipes. Everywhere I have been for the past 55+ years, "M" has been the material of choice for domestic water piping.

i'm originally from the east coast

type l was always used in my and everyone elses new home.

only place you'd see M was feeding hydronic base board