No consensus on that question really, but I do have some interesting results to report on my “experiment.”
To recap, I transplanted three Orange Grove seed-sisters and one OG x GG4 into 3 gal bags sitting on micro octos. The soil for each was a mix of Promix and Perlite. I varied Promix & Perlite ratios in each pot and recorded how long it took for them to extend their first root beyond the net pot.
That was nine days ago and, happily, all four plants have found the Octo rez and they are all blasting off as only octo plants do.
The surprising (at least to me) outcome was a clear progression of timing in when the plants first put roots into the reservoir that seems correlated to the amount of perlite in the soil mix: the less perlite, the quicker the roots hit the rez.
Here are the plants on 1 September. You can easily see the decreasing percentage of perlite in the mixes.
Clockwise from the lower left, %Perlite - %Promix
1 - 60% - 40%
2 - 50% - 50%
3 - 40% - 60%
4 - 25% - 75%
Here are the same plants on 10 September. On this day the last of them finally poked a first root through the net cup.
So here’s the layout again with the “First Roots” noted
Clockwise from the lower left, %Perlite - %Promix
1 - 60% - 40% September 10
2 - 50% - 50% September 9
3 - 40% - 60% September 4
4 - 25% - 75% September 2
Make of it what you will OctoPoddlers, that’s a pretty clear correlation: Less may be More when it comes to perlite in your Octo soil mix… at least when it comes to how fast they hit the rez.
Does it matter? Dunno, but here’s a comparison of the root systems of plant 1, (60% perlite),
…and plant 4, (25% perlite) as of this afternoon.
Paz y amor amigos,
-Grouchy 
–Addendum–
In checking my logbook I realized that the four seedlings in the pictures were actually transplanted into Octopuppies on 28 August, so the first one to hit the reservoir on Sept 2, five days later. The last one put its first root in the rez 10 days after transplant.