dont mind at all my friend, na i dont mind if the roots touch each other, a few people have asked me this and i dont really see the downfall? why not let the grow out all over the place and stretch to where the want to, let em get all tangled up. i water the ENTIRE soil bed at the same time, till i get runoff. so they are all seeing the same water/nutrient levels, yes there are a few dry and wet spots, but thats hard to avoid, you have to be very careful and to put the soil down evenly or the water will want to drain through the looser soil, leaving the packed soil dry, eventually it will then reverse, the packed soil will slowly WICK water every time yo water feed then that tightly packed soil will want to stay WET for a longer duration. i believe if anyone attempts these beds the first thing i suggest is a good wand that showers water and to water the bed slowly as so it doesnt puddle up making the water find the path of least resistance and creating canyon like things in the soil where the water just runs through not wetting the soil around it, if you follow. important to water evenly and let it saturate, then reapply, saturate then reapply, that way you know your drenching the entire soil.
and the reason i trim the bottom half is a most of the time that bottom growth doesnt receive nearly as much light and usually ends up turning into larfy fluffy buds, that really arent filled out and mature. cutting the lower growth helps concentrate energy up to the big 5-10 top nugs that receive the good light. then all your final product ends up looking like all good top shelf donkey dick nugs. not a bunch of dime sized ones. (although some people like that, but its the big buds that sell)