I've sailed navy 27 foot whalers with no booms. It's OK with a gaff rig, the gaff holds the main out when you bear away to sail down wind. With out the gaff it would be hopeless!
The Hobie Getaway has a boomless main and while controlling the sail is somewhat problematic this is mitigated by having a full width traveller. I found the system to work reasonably well, at least as well as anything Hobie can work.
It depends on what you call "done right". You can't get the same sail control without a boom. Many years ago there were some high performance cats without booms but even there they have found a boom allows more control over sail shape, angle and twist.
The boom can also take lots of the load off the mainsheet, making trimming the sails lighter work.
The picture of tan sails and the junk rig brought memories. I sailed on Burong Bahri from Bali to Nusa Trengannu in 1978. the good thing was you could pull in and get new booms.
