3/4 supply.....1/2 section.....3/4 run....

" ... I really like those charts about the copper ..."

A master plumber saying he's impressed---that makes my day.

/kop

If it's difficult or serious demolition to eliminate the 1/2" then as MPM suggested, plumb it the easy way... It will take 15 minutes longer to go back and replace the 1/2 with copper than if you did it in the original install... if it don't work like you want then stick the 12" piece of 3/4 in later.....

Now it's 3/4 ALL THE WAY!

I finally bit the bullet this weekend. I heated up the old tee and took it out, no problem. Somehow I was able to get enough indirect heat on the new copper fitting (from the extremely small access point I had to work with) to melt some solder (I made sure I used about 6" of solder just to be safe, since I couldn't see the joint and I could barely fit the solder back there).

I did have to (blind) shoot the fire extinguisher a couple times into the wall cavity, though!

Presure test worked, didn't burn down the house , and now since it's all 3/4" I don't have to worry about any restrictions (even if it's not a dramatic change, it always would have been in the back of my mind that it could be BETTER!)

Thanks so much for all your suggestions!