The railings look great. The larger diameter will also make a deck ape feel a little more comfortable in rough seas.

Has anyone used hole cutters for coping. Go to www.mcmaster.com and access page 2366 in their online catalog. These are normally used with a mag drill but I have had greats results using them in a mill or even lathe. these cutters are precise with negligible runout and are much heavier than a hole saw. It would take a lot of cuts through any tubing to wear one out.
the carbide would last until you chipped it.

What little coping I have done I have used my milling machine. For small stuff, 1" or less I have used an end mill with great results.

Speeds and feeds is everything in making a cut, not matter what cut you are making. Lubrication and/or coolant is a big factor also. By the time you know your cutting tool is hot, it is too late.

What kind of boat is is going on? Keep the pics coming.

Grits