IMO, It's not so much that it would be
HARD to balance it, It's more the amount of time doing the balancing could be used elsewhere.
Besides balancing and tweaking abilities to help the balance. It's not that bad of an idea IMO, another problem is the coding you would have to add to make it work.
Personally I think it would be a cool escape ability to make a waygate or something for 5-15 seconds that could move more than just your own builder, sort of like Satyr being able to invis other players. except you could actually help your allies escape the entire base. (sort of like the zergling building is SC1)
Kind of an overpowered idea, but it would still be fun.
Coding time + Balancing Time = ouch
