I could definitely see the HLF as being a great cab for outdoor gigs. All those extra lows and reduced mids would end up about even out there whereas indoors they're just too much.
I play outside quite a bit, and voiced my diy speakers to sound good out there without having to boost a bunch of bass...works great for me. They're not as bottom heavy, or I should say not as mid shy, as an HLF, just lean a little bit that way. Mine are still useable indoors
. But the HLF would be a great choice for a big, open air festival stage, or even small patio stage, with no backdrop. Just having them sit outside would pretty much turn everything I don't like about them into things I do like about them. 
I play outside quite a bit, and voiced my diy speakers to sound good out there without having to boost a bunch of bass...works great for me. They're not as bottom heavy, or I should say not as mid shy, as an HLF, just lean a little bit that way. Mine are still useable indoors