It could be done but it would be very complex and probably questionable accuracy. Once you have COB spacing, power and PPF figured, it would require that we adjust the inverse square law for each particular beam angle, how much light was hitting the wall, how close are the walls and how reflective are they, are there walkways on certain sides of the canopy, where is each COB in relation to the wall. All those variables would really start to come into play if we increased the distance to canopy beyond the "sweet spot" for that particular lamp. So the ideal distance to canopy is not very adjustable once the lamp is built. Rather than changing distance to canopy, you could dim the lamp down or boost it and the PPFD would change, but the height would not need to change.
So if you want to increase the distance to canopy you could use narrower lens/reflector angle. If your design has the COBs packed closer to together, increasing distance to canopy will help improve uniformity and coverage, and that would require a narrower lens angle to keep the light off the walls as much as possible. If you are designing for a larger vertical height I would recommend lenses over reflectors. This would also allow for fewer COBs run at higher power. This results in a less efficient use of floor space but maybe an easier space to work in.
If you want to decrease the distance to canopy, you would have to spread the COBs wider to improve uniformity and use a wider lens/reflector angle. For short distances to canopy reflectors may be a better option than lenses. If you are running short plants and short distance to canopy this may open the possibility for a shelf system to make better use of floor space, especially doable in veg. This design would perform best with more COBs, smaller COBs and/or running them softer. This approach can improve the space efficiency and electrical efficiency of a grow, but can result in an larger more complex fixture like my "heatsink armada".
