I can't speak to the intricacies of the Z5's "progressive" footage, as I've not heard anything about it. However, PrPro is excellent in its ability to edit pretty much any footage from any source on one timeline side-by-side. Assuming both your sources are the same native frame size, you'll have no problems. Even if the aspect ratio isn't the same (1.0 for true HD to 1.333 for HDV), it'll still work great. Even if you have some in interlaced and some progressive, it'll still generally work just fine and give you good results. The only part it doesn't do well with is if you have footage of mixed frame rate (29.97 vs. 25/ 60 vs. 50). But even there, you can right click on the clips that you want to change and select Modify > Interpret Footage and there you'll be able to force it to a particular frame rate so they all match.
Though I can't speak to the Z5's progessive thing, I used to shoot with a Canon XHA1. Their 24f was supposed to be "progressive" but wasn't truly so. I never had a problem with editing that footage in either interlaced or progressive timelines.
Not directly related to your post, but just FYI, if it's helpful...
I just finished a project with mostly HDV footaged that had already been converted to ProRes 422, but still interlaced (29.97) and 1440x1080. The timeline was interlaced. I had a bit of footage from a Canon 60D (24P), and a little from a Panasonic 160P (29.97p), both 1920x1080. All looked fine in Premiere, the AME interlaced output/master (ProRes) had a very slight studder on the 60D footage, but once I ran it through Compressor (4) and used the frame controls to do a clean deinterlace all looked fine.
I was told, in one of my previous posts here, that a project with mostly progressive footage with a bit of interlaced would not look as clean and needed to be deinterlaced.