While I'm a lens owner myself (bought as a test and kept it ever since) there is something to take into account that seems to be glossed over on many of these threads: Changing the zoom of a projector will very often change the brightness of the image as the aperture changes on the projector's lens. When using the lens I have to reduce my zoom to minimum which gives me a reduction in light output compared to if I zoom. In my particular setup there is little measurable difference in the lux measured at the screen (Tecpel 531 lux meter) when zooming or when using my (Isco II) lens, so having more light output with a lens is not a given.
However, I have a particularly long throw setup which tends to exacerbate this issue, though it also means I get minimum pincushion, maximum contrast (due to that same projector lens aperture change) and a nice sharp image due to the smallest area of the anamorphic and projector lenses being used. Simple maths using the 33% figure doesn't always result in a real world increase of this magnitude as I found. However, I still prefer the image using the lens rather than zooming possibly due to a mixture of lack of overspill ( I can't surround my electric screen with black velvet), higher contrast due to the lens aperture effect and higher pixel density (even though I can't see the pixels when zooming, the image still seems more 'solid' for want of a better description). As said I bought my lens to try, knowing I could sell it on for little or no loss, but I chose to keep it. I could have used the money to improve other areas of my setup, so it's not a decision taken lightly or just to 'prove' the lens vs zooming argument in my favour as it's just what works for me, in my particular setup.
In a short throw setup the negatives of a lens could impact much more on the result (more pincushion and possibly a softer image as more lens area is being used in the A lens and the projector too), plus these days we have the option of E-shift or 4K projectors and lens memory options which might reduce the A lens improvements (bar the overspill which would still be an issue for my setup).
"Don't believe everything you read on the internet". William Shakespeare 1615