OK,
With a little searching I found out what thread you are talking about Bayoupr. The thread was moved to the proper forum because it dealt with lighting, which is a product. We are trying to keep all the related posts in the related forums so that threads do not get lost in the general forum. This makes it much easier for everyone with a little bit of organization.
To answer your question:
You will see a difference with each set up. The 50/50 bulbs are brighter than the combination of the two. You will definitely see a much bluer tank with a combo set up versus using 2 50/50's. If it were my tank, I would use a 50/50 and a 6500k daylight bulb being as this is going on a FW tank. The 50/50 bulb will simply be used for color enhancement.