Or you could buy a nexus 7 for $240. I know, it all comes down to taste and ecosystem, but it doesn't hurt to mention it anyway.
The larger screen is a huge plus for the Surface Pro 3, but I don't really need it as much because I have a laptop with a much larger screen that I use most of the time at home.
You know your needs better than anyone. You also know your WANTS. Maybe I'm reading too much into it, but it almost sounds like you're trying to talk yourself OUT of getting an SP3. I'll offer the advice my wife [with saintly patience towards my tech addiction] always gives me:
"Don't settle. Get what you WANT, or you'll never be happy with it and you'll always be frustrated over what MIGHT have been"
This is USUALLY followed by "And I don't wanna hear you whine about it for the next 6 months...."
I love my wife