Thx for the test James, I'm dubitative with this conclusion tho. A wider colorspace only allows for a slightly better GI (corona already benefit from that). The lighting part you mention in Vray is the consequence of the tone mapping curve embedded in the ACES view transform.
Lupaz is right, the scene needs to use the same lighting (free hdri or constant color) and the same assets (I see the widows suddenly disappeared in the Fstorm scene). For those who are wondering, the textures are from the corona library. Also, matching the initial exposure is important to start on a similar basis imho.
I made a quick test in Vray with this HDRi :
https://hdrihaven.com/hdri/?h=reichstag_1camera : iso 1600 / F-number : 4 / shutter speed : 1/50s
Default sRGB :
ACES view trasnform with sRGB primaries (so no texture conversion) :
sRGB + Highlight compression + Handmade curve :
It took me 10s to build the curve by hand to my liking and it's really close to what ACES do and I still have control over the curve and the highlight compression.