The rounded glass is Holophane #4252 and was the standard glass for the Powerlite small luminaires, Line Material/McGraw-Edision luminaires, and AE 13 until the late 70s. Some early OV-15s used this glass too. Then the square glass took over. The square glass looks good on the L-150, OVS, and OVX and looks good on the OV-15 silverliners but I prefer the rounded glass on everything else.
Here's my 113 with the round glass. Indeed it does look really good. In fact, the 115 spec sheet shows the rounded glass where it has the specifications drawing of the fixture on the bottom left of the first page. Seeing that Holophane and AEL are owned by the same parent company, I'd imagine you could custom-order a 115 with the Holophane #4252 refractor. You might have to buy a certain quantity but I'm sure they'd do it.
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Here's my 113 with the round glass. Indeed it does look really good.