Thanks for all the great responses! I think XCrispi made a very relevant point - light penetration is the key and all the height in the world doesn't matter if lights not getting where it does the most good. I think for this grow I will just top them and next time I'll LST/top and compare notes. I'd like to have more room horizontally to properly LST and my next grow will be just 4 plants.

I've already followed JustaSeeds incredible scrog thread - excellent example of great yields with just a few plants. It was fantastic to watch and it helped reprogram my "more plants is better" mentality. Scrog is definitely on my to-do list.

Also been following your great examples Splifted - awesome job!!

I just inherited a wardrobe cabinet 18 x 30 x 72 - maybe I will try cloning GK! That should be plenty of room for a mother and a cloner.

Thanks again to everyone!