I have a thing for ventilated grips. I like them. They look great, they feel good in the hand and most important, they allow more rod flex into the grip.
These grips is another thing I have picked up from the old bamboo rodbuilders, who I have a huge respect for. I use epoxy to glue them to the blank. Then I use waxed coins between the cork rings. Before sanding I use thinned wrapping epoxy with a syringe to inject and "secure" the cork rings a second time.