I personally think it's easier to set text in Quark, even if it's related to a graphic (unless, of course, there are transparency effects, etc). That way you can work mostly in Quark and only use Illustrator when you need to adjust the images.
As I ponder your question, my inner pre-press personality surfaces and I can think of a couple of minor problems you could encounter by placing outlined text into Quark. When you create outlines on smaller point size fonts, they get heavier; bolder. So if that's an issue, you should the set text in Quark (or don't convert to outlines - but be sure to include those fonts when you send the file to your printer!).
Another thing is, depending on how the piece is going to be printed, some printers may have trouble trapping text placed from Illustrator. If you go to a smaller shop (like mine) who can't afford or has little use for expensive in-RIP trapping software, there can be problems seperating Illustrator images. They knockout by default, except for black which you can set to overprint. But if you use a spot color for your text block (not sure how process colors are handled), it will knock out whatever is behind it when in Quark, which can make it very difficult for the press to register prefectly. So, you may also want to check with whoever is doing your output.
Hope this helps!