New setup looks great HDS. I like the transparent tubes too, I considered adding a few pieces on purpose just to be able to take a peak.
I agree with your point in general but a slight increase in gpw is feasible. The thing is, when you run bare bulb you don't have reflector loss, i.e. the reflector itself does not reflect 100% of the light. The led guys claim up to 20% loss, so it's probably more around half of that
which is still a 10% loss. That's potentially a 10% increase in gpw, but obviously doesn't make up for using a much larger surface. A couple of dozen pages back I mentioned a few things about this too, suggesting HDS roll out the inner canopy of his octagon, convert to a flat surface to get a good idea of how much light is ideal.
I.e. if the canopy is 3 feet high and 12 feet radius you got 36 feet to cover. 2x 600w would barely work in that case, 3 would be better. If the canopy is 4 feet high and radius is 15, 60sqft in total, then 2x 1k watt could work very nicely. Get roughly 5x5 per 1k watt normally, so two are good for 50sqft, add the lack of reflector loss and it should work nicely for 60sqft in a cylinder canopy around the bulbs.
"less space required" can result in more yield from the space you have available, but yes, generally only when adding more light to make up for spreading it out over a larger canopy. That's the key issue, the spread, the resulting ppfd is what matters most in this context. By removing the reflector you instantly reduce the ppfd drastically.