The 2700 offers a few more features than the 1700, such as networking abilities, USB interface for flash drive, offers composite video switching when using Zone 2, and it scales HDMI with ABT. The power difference is neglegible, the specs say the 2700 has 10 watts more per channel, not going to be noticable.
It all comes down to price. How much can you get them for? If the 2700 costs more than $200 more I would get the 1700. But, then I don't know if you need the scaling feature.