The moment of truth! My Orange OBC115 arrived this evening. Initial testing proves this cabinet to be an absolute sound cannon; it has a deep low end that goes up to a strong upper mid content, then rolls off after rather sharply. I did a quick side by side with one of my Rumble v3 2x10 cabinets and the Orange's more round, vintage voice contrasts greatly with the Rumble's comparatively even, almost hi-fi (in comparison) sound. I feel like I could get away with having my Tone Hammer DI's AGS circuit disengaged with this cabinet and still cut through the mix like a knife (in fact, I found myself rolling off some of the upper mids with the Tone Hammer to even out the sound). I have a gig coming up this weekend, which will be trial by fire, so I will reserve further comment on the Orange cabinet's performance until afterwards. Also, the Rumble cabs are still keepers, so don't interpret this as me putting them down at all; just another tool in the box!
As for the main topic of this thread, I tested the Orange 1) flat on the floor, 2) on the floor propped up with door stops, 3) on top of my SKB utility case, and 4) on my On-Stage RS7000 amp stand. Flat on the floor, it felt like an earthquake but lost definition. Due to the cabinet's more than 18" depth, the doorstops don't angle it up very much to make an appreciable difference (they do with my 10.5" deep guitar cabinet, though). The cabinet had LOTS of volume and definition raised up on the stand, but it's simply too big to fit safely on it, even turned on its side (port facing downward). I would definitely need a T-stand or flight case lid to safely raise this cab.
The winner for my at home testing was on top of the SKB utility case. It still had the lows, slightly better definition, and is perfectly stable. Plus I already haul the thing with me to every gig so it has that going for it! I'm also betting it'll be good for those hollow stages and wood floors to avoid hearing structural damage happening to the building over the sound of the amp. That said, I may still consider a T-stand down the road if I find myself running out of headroom with the Orange, but I doubt I will.
And now, pictures or it didn't happen! You can copy my amp and pedal settings, if you like