I am sure you will get hammered with responses to this, there have been many threads out there about all forms of Interactive Whiteboards and the pros/cons to them all. Ultimately what you will find is a debate similar to Republican vs. Democrat or Mac vs. PC. Lots of vitriol and marketing spin on both sides as well as passionate users.
I do work for SMART Technologies, so I don't want to portray myself as something other than that, but I encourage you to get a hands-on with both boards and use them in your classroom with your students. Most companies have a program that will allow you to do this, and if you'd like more information on this for SMART, I'll be happy to help you out with that.
These are all just tools and depending who you talk to, they'll be portrayed in whatever light best serves their bottom line. The only light that matters is the one in your classroom, with your students when learning is taking place:)