Right, bit late comming, but:
The null texture:
Its INCONCLUSIVE
The null texture indeed, works.
But, and this is a big but, it doesen't seem to make any big difference in the example maps, however, in larger maps, it makes an enormous difference. I won't include those larger ones as examples for obvious reasons...
It also has the effect of reducing bsp size, the first map, is 200KB (No null textures) the second one is 180KB (with null texture stripping)
This is a very small difference, but if you apply this to a larger map, this means you can reduce the bsp size by up to 20%
The wPoly reduction is a mere 30 to 20, very small, but this was with full vis.
Most people run normal vis, which means the reduction will be a noticable one.
However, the fps rate went up by 1.5 frames on average...
So you see, if you don't use it, you're not missing much, but if you do use the null texture, then be aware that it only makes a difference in large quantities.
(i'll upload those example maps later on)
And loque: Check your spec, if your comp is less than a month or so old, you can run every map with no problems....