That makes sense. The ILDA website is trying to ensure that promoters don't sign off on an under-powered show that will look lame. In the other thread you started, I also assumed you were thinking about a commercial show, which is why I initially recommended higher powered lasers. But for home use, it's just not an issue because you can always control both the light level and the fog with great precision.
As a general rule, you look at beam diameter and divergence. Lower is better in both cases.How does one quantify beam quality?
A typical 2 watt projector will have a 3 to 4 mm beam at the aperture and roughly 1 mrad divergence. Anything over 1.4 mrad is a sign of poor quality, as would a beam diameter larger than 4.5 mm (at least for this power level). Some higher-quality units might have tighter beams.
Adam