I haven't tried either of those cold cut saws but assume they are constructed the same as thier chop saws. The dewalt chop saw has a thin stamped steel table and isn't all that sturdy. I really don't like the handle on the milwaukee because it is turned the wrong way to be ergonomic, unless the saw is low, (For me anyway) but the table is much sturdier. Again, this is the abrasive chop saws I have experience with, but I believe the cold cut saws have the same drawbacks.
As far as quality and speed of cut, that is going to be more dependent on the blade.