anyone use the big mama blocks?

I'm wanting to try out some rockwool growing, but have concerns about using just a 6x6 block. I grow 2 or 3 plants at a time under a 600, and try to get a nice 2x4 foot scrog. From reading the info at grodan, they suggest against using the big mama block 8" with ebb and flow. They say the top half will dry out too fast, and suggest a top feed only. If I top feed, does it need to be a slow drip? or can I give a good volume of nutes 2 or 3 times a day to simulate the watering cycles of ebb and flow.
If I don't get any info on the big mamas I may try using a 4x4" block on top of a slab. If anyone has some good info leads for me, or links to a journal or something , I would love to see them.

I wouldn't do a top feed with your e&f. Kinda seems silly to have two systems in place, imho. Would your e&f come up to the top of the 6" blocks? If you really want to use the 8" blocks change the height of the drain or build a new system to accommodate the 8" cubes, let it come almost to the top of either cube, about 1/4" or so. rockwool is easypeasy. good luck!