People, people, people, calm down. None of us here have an iPhone 6 Plus yet, it comes out Friday. Ask your question then or walk into a store and try it out for yourself on Friday, thats this FRIDAY September 19th, which is now 2 days away.
Yeah you should be able to type just fine. We will find out on Friday for sure though. I'm also a guy with big hands and that is why I ordered the Plus. Let me put it this way, I can wrap my hand around the iPad mini comfortably so I should have no problem with the Plus.
When I type on the 5S (or any touch screen phone), I type in landscape mode. I find that in landscape, the buttons are much farther apart and I make less errors.