Both should satisfy you. I bought the 1400 about 3 months ago and am not sure I would have apreciated any of the extra features offered with the 2400.
I was looking at the rxv750 which is also a lot of bang for the buck, but I liked the zone 2 amp for another source to another room and potential for zone 3 if I ever need it.
Specs for the 1400 are nearly identical to the 2400. You won't hear the difference between 110 and 120w. It's solid, sounds sweet, processor for theater is great, the direct mode for 2 channel is very clean and I think the value is hard to beat. I didn't get it at a web price, but I got sound advice to go to $699 and I'll get the Yamaha warranty, which you won't if you buy on line.