My experience with upscaling has largely been a positive one. I'm using an older samsung that, while obviously flawed, has definite benifits. You will find a significant increase in the sharpness of the picture, especially on that dlp.
Be aware that these things are rarely perfect and I had to go through three units to find one that didn't skew my colors. Also, once you get the right unit on a properly calibrated monitor, they are extraordinarily unforgiving of weak source material. Occasionally, I have been able to tell a director's afterthoughts or scenes shot with inferior film stock because of the pronounced differences.
All that having been said, the options for DVD-A/SACD are worth the cost alone and if the particular film of choice can't bare scrutiny just flip the upscaler off.