.689 is a little big more some paint. But then again I have a barrel kit, so...
Sometimes its better to go with a kit even though they are more expensive. But i think a .689 back is the best all around.
The stock barrel for the ETek is a .693. I'd say get .688 UL (since they come in that instead of .689) or maybe a .690 if they make em in that. That way you'd have a barrel for small paint and the stock barrel for everything else. The stock barrel works great. I had a barrel kit till I found out all I would mostly need is 2 barrels. Now I have the stock barrel and a 1 piece Proto barrel (they all come in a .690 size). They shoot just like a UL and are cheaper as well.
And then the Canadiens said, "Lets just ask them nicely to leave. If they don't, well beat em with our hockey sticks."