Hi Yorkie
I have done both in both. What I have always done however was try to support the wire as close to the decking as possible.
The only concerns that were ever raised were, the bundling effect with the AC90 (sheath currents) and FT rating in the case of plenum wiring which AC90 is suitable, at least it used to be. Not sure what the FT rating of a ty-rap is however. Nothing marked on the package that I have here.
It has been years since I have done that kind of work so please take my reply as old experience and not gospel.
Cheers
