The op will have no problem at all fitting his luggage in a taxi.
As much as luggage on line 2 sucks, it is doable. As I mentioned up thread, I think the op could endure the drill ONE time, assuming no transfers.
If I were the op, I'd stay at ruijin both times, and do taxi to maglev one time just to check it off the list.
That having been, swapping in century park or ic pudong on one of the visits makes sense if he's too tired to do anything interesting and/or the savings are substantial.
Off topic, zhabei is going to be cool about 2 years from now because wpp moved there last November.