Where do I begin, Judy! (by the way - I love your picture!!! I haven't been able to find time to post here much and haven't seen it before! )
I think the most significant improvement over the DeWalt is that there is significantly less front to back movement in the blade. While it needed some initial adjustment (they all do - I think it is part of the set up process) I can't believe how much better a sawyer I am with this saw. I really thought when I heard everyone saying how they would "never go back" that they were just blowing steam. But now that I have the EX, I truthfully and honestly think it is worth every extra penny. If you get the saw from Ray Seymour at Seyco, I believe he sets this up for you initially before he sends you the saw.
You can turn so easily without it 'catching' from the front to back motion, and this allows for the most intricate cutting without worrying the piece will jump around or get caught and slammed on the table. (you know what I mean) That lack of motion allows you to follow even the most detailed pattern easily.
Since April when I got my new saw, both my partner Keith and I believe our scrolling has reached a higher level. I know that sounds corny, but it is the absolute truth. Diana Thompson says the same thing, as does my friend Leldon who has been scrolling for over 15 years and also has been published in the magazines. Both of whom I have a lot of respect for and their opinions weighed heavily on my decision to get the EX21.
If you have any more questions on specifics, just ask. I will be happy to try to help or others here will too.
Take care, Sheila
