The denser the negative the more contrast difference you will see between the two. I get about a 1/2 to 3/4 of a grade more contrast from the condenser head with my normal negatives. It also seems that the condenser alters the effective shape of the curve a bit over diffusion, so it's not always possible to match prints between the two; you can get any two points to match, but not the entire image. That's just my observation, but I haven't seen it described elsewhere, so maybe it's user error or something unique to my system. Neither is consistently better than the other.
The sharpness issue is overblown in my mind. I can see it, but its very slight. So is the dust issue. I need to spot on both.