I'm the base monkey for my SG. The base editor is probably my second favorite element of CoX, and I've easily spent 50 hours editing my SG's base. And though I also love making costumes, there are many, many differences between the two. Aside from the obvious visibility and personal/group issues...
--1) There is no piece of my costume that I can't get back immediately if I decide to try out a new piece. If I want to see if I'd rather have a ley tap or a turbine generator, I have to destroy one to see the other.
--2) I can click 'back' to immediately undo every costume edit, or 'reset' to undo any piece. If I decide that, having moved everything in the base, I really just like the way it was before, I have to manually reposition every object, sell and rebuy every decoration, etc., etc.
--3) There's no costume part that requires playing Tetris to fit with the other costume parts. Since there's no 'off plot' storage space, if I want to swap the infirmary and the workshop, I have to figure out at least one, usually four or five, intermediary configurations that keeps everything connected while still leaving me room to place the next room.
--4) There's never a costume edit I try that is rejected by the costume editor. If I want to change my costume bottom, it's done with one click. If I want to move my medbay across the plot, I have to move every object away from the walls of the medbay and the room I'm trying to attach it to, and then hope and pray that the base editor will allow me to make a doorway where it seems like one will fit. If one won't fit, it won't allow the move, but it won't tell me what stupid piece of the base is blocking the edit, leading to hours of trial and error. It's usually easier to delete the room entirely than it is to try to move it. But if said room has crafted items, that's a no go.
--5) Almost every costume part is immediately unlocked and available. Bases have been out a year, and the Fusion Generator is still not unlockable. My SG has been around 10 months, and we still haven't unlocked the 2nd level infirmary upgrades.
If the base editor is like anything, it's like selecting your powers as a newbie. The descriptions of power effects are only marginally helpful, just like the descriptions of base items. What's the range of an elite chill cannon? How big a room will it take to fit the AES? Does having multiples of this item stack the effects? These are questions for which there are no documented ingame answers.
The ingame help is purposely vague, just like power descriptions, and thus almost useless. How many people thought Jump Kick would be a useful power when they read the description? How many people thought that the energy curtain would work on their turbine generator? There's no way to find out that Jump Kick sucks or that the energy curtain won't work other than 1) trying it out yourself or 2) heading to the forums, where dedicated players do the jobs of the game designers and provide documentation.