as said..... anodising is full coverage protection whereas paint doesn't give that level of protection.

Another big disadvantage is that the paint chips quite easily, right in the area where the mast lays while you are attaching the shrouds prior to standing the mast or de-rigging the boat.

and one I hadn't figure on, the painted beam is slippery as heck when wet and that makes it a lot harder to clamber back on deck after a capsize..... ofcourse this isn't an issue if you don't get the boat wet or capsize it