I've done a bit of tinkering with lights on a unicycle. Like you, I've come to like omnidirectional rear lights. HotShots etc are great on a bike, but on the uni my frame isn't always perpendicular to the ground (climbing, descending etc) so I can't quite be sure where a directional light is pointing at any given moment.
At the moment I'm running a NiteFlux Red Zone 4. I run it on the solid 1W mode at night (~64 lumens) and flashing 4W mode during the day (~250 lumens). It's not as dazzlingly bright at a distance as the long throw lights, but it makes up for it by being more predictable in brightness as you approach it. When I'm cruising at night I really like looking down between my knees and seeing a big pool of red light on the ground.
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