Alex: David: Maybe it's the ABR's being free that makes it possible to sounds so awesome outdoors, and keep a coherent level of bass. The sound muddles when you turn them up in a confined space.
That goes for almost all speakers other than BeoLab 5s. However, I'm impressed that 3s managed to sustain a decent amount of bass outdoors.
Of course, you can't be yards and yards away from them. The energy dissipates quickly when there are no walls. On the other hand, absolutely no risk of artificial boominess. For my preferred use, it's perfect to be outside, as you can really dive into the music when there are no primary/secondary/tertiary reflections to take the edge of the direct signal - and the bass is there. (These are quite special, in that they have the soft-rubber vents working away and shifting air).
All in all, a very pleasant experience.