Sorry I misspoke above and Hortistar is the reflector I meant, just bad with names. If you want a more rectangular footprint, those will help, but keep in mind the CMH lamps are more of a single point of light so they don't light up the reflectors the same as a long HPS rod. That's why I think the vertical style with square footprint are more efficient, the Grobal looks to work similar since it puts the little sphere of gas in the right place (and the price is fair).
I know you guys like 3x3 for veg but I'm seeing they need to be closer for flowering, like 2x2. The ones in my tent are in Irradiator hoods and vented with a small fan, since it's a sealed test with CO2 and optimum VPD. I'm sure there must be some loss from the glass, especially any UV, but I'm not seeing a big difference in the flowers yet (now in wk7)