The major difference between the two is that you can place a fully charged pack on the Novak. The Rayspeed does NOT recommend doing this. However, I have taken a pack after a run and placed on the unit without any problems.
The Rayspeed has two modes. An equalizing mode and a conditioning mode.
The Equalizing mode discharges at 5A down to 0.9v
The Conditioning mode discharges at 1A down to 0.1v
There is NiMH and NiCD switch with a fixed 0.9v or 0.01v shutoff respectively on the battery type.
The unit comes with a nice fan and works as designed. I have been using the Rayspeed for three months without any problems. The Rayspeed unit uses thumb screws to make contact with the batteries the Novak unit uses tabs. Some people have complained that the screwed had worn out quickly, I put a tiny bit of dielectric lub on the screws and have not seen a problem.
The Novak is pain with certain pack configurations.
I race with others who have the Novak and we have swapped units a few times and I cannot say that either of us have seen a major difference between the two in terms of battery performance. They both do the same thing in that sense and they help keep the batteries matched.
The Novak units benefit is the adjustability -- it all depends how much more important that feature is to you to justify the extra cost.
I own two Rayspeeds and I have used the Novak for several weeks at a time and I would say they are both very good units its a matter of what features are important to you and how much you want to pay for them.