the one in the original post doesnt have anything in common with a steadicam merlin. its based around a 3 axis gimbal, the same as a high end steadicam.
the second one is a merlin clone, but im not sure where the "incredibly expensive" comment comes in. its only a few dollars more than the ez steady was, and less than half the price of the merlin, neither of which come close in performance to a traditional properly balanced gimbal setup.
the modular beam doesnt make it complicates. when you buy a system, generally youll just have the one. the extra beam is only to make it easy to change from a very light camera - like a goPro - to a very heavy one, such as a 5D. its not something youd be changing out often (though you could if you felt the need).
for reference, i designed the microsteady, so if you have any questions or critiques, feel free to ask.
oh, heres a teaser of the early prototype, which hasnt been posted yet on kickstarter:http://microsteady.com/images/IMG_7020.JPG
this little guy (with a canon 5d moutned) had the DP of "House" drooling.