The regulation machines throw targets faster, and because you can move over 40 yards from each thrower, you can shoot targets that are thrown from above and behind you, incoming targets, or targets that pass broadside at angles of up to 90 degrees, as well as two targets going in opposite directions , on different trajectories. With sporting clays, the variety is even greater, as some targets bounce on edge on the ground, and some are thrown straight up, and some are launched from up to 100 yards away. It comes down to whether you want a real challenge, or if you are content to shoot targets that would be extremely boring for a competent shooter.
Sounds like it partially depends on the trap set-up at the club. Like i said, i haven't used ours, but i do know that there's only one machine in a fixed position (a bunker) and the shooters must stand at set shooting stations in a row behind the machine, all shooting in the same direction over top of the machine and towards the field in front of it. Sounds like some clubs have more active set-ups, but i'd imagine that varies from club to club, no?
Either way, i said i love it, but i'm sure not very good at it, i'm usually happy if i can hit 50%. So while the DIY set-up might be, as you say, boring for a competent shooter, it's still pretty exciting for me. Come to think of it, that's almost an argument for not getting good! Maybe ignorance really is bliss.