Cannot help you with this question, @icebeng, since I have not used my WF with a rolling bag. Perhaps another Forum member can chime in. I think there might have been a thread discussing this.
No worries, if I do get the rolling luggage version, I'm likely to use it the same way you do, so how it fares on top of a luggage will not be a major deciding factor.
Thankfully(?) , there are no rolling luggage options available right now for sale, so my wallet is safe!