i ride the open pros and i really like them..
i think the full eyelet on these rims definitely adds to their strength..
aside from strengthining the spoke hole, it is basically like a tube that goes through the rim, and i imagine it helps distribute stresses on each part of the box section..

here is a pic of an open pro cross section i made after my front wheel got run over (the rim actually held up quite well with no cracks or spokes pulled through:


the only problem i've had with these rims is the 'click'
the open pros are pinned or something before they are welded, and sometimes the metal bit that spans the joint comes loose so once in a while at very low speeds (walking) it might make a click sound... i've heard of people resetting it with a hammer and punch but i haven't actually been bothered enough to try yet...
this has only happened to me with one rim out of maybe 3 wheelsets

i think people like the velocity's for their colors and non machined braking surfaces among other things..
i'm sure they're a good company too..