Alex,
I will echo Zac's thoughts. I like the individuality of the damping between tubes and shock. I find that with CRC tubes, that the clearance is just right to use regular shock oil. I use a few drops of X Ray 50wt on each tube. Trinity purple stuff also works great. I find that heavier side dampening speeds up steering response, but if you have a track lay out with chicanes, too thick may hold a tweak by the 3rd turn. Going lighter will slow down steering response, but you should get a little more steering exit out. Probably just the opposite on center oil if you are going to tubes from a disc. Disc, if you run lube, has dampening 360 degree which will factor into your center dampening. To get the same lateral dampening when going to tubes, you may need to oil up in the center shock.
But it's all about the feel! ... and the lap times.
Brian