I've used Topaz plugins for a number of years. Most I feel are very good and use several in my daily workflow. One of the Winners is AI Gigabyte. I have used a number of upressing plugins over the year -- I own Photozoom 6 and have used On1 Perfect Resize since the days it was Genuine Fractals by LizardTech. AI Gigabyte really IS a big improvement on those. While it is not perfect in every instance, and in fact can vary on the same basic image each time you run it, the fact is that it seems a big leap 85% of the time. As my own test, I enlarged an old E10 4MP JPEG image from it's native nominal size of 7.5" @ 300dpi on the long size to 26+". I did the same with Perfect Resize. Here are the results.
And now the Razzy. Topaz JPEG to RAW AI. I'll be honest, it sucks. It essentially encapsulates the original in a DNG. Big deal. Lightroom does that too, and better. On a recent job I discovered that I had not switch my camera back to RAW+JPEG after using the camera to scout. As a result, about the first 40 frames or so were shot JPEG only, until I caught the mistake. The lighting was tricky and unfortunately the client chose a JPEG for me to do for final print quality digital imaging. I had just received an email about JPEG to RAW, so downloaded it as a trial. Imagine my surprise when I imported into Lightroom and found it to be crappier than the JPEG (which wasn't horrible). Still, I pressed forward. But achieving better color balance/white balance was severely limited compared to a real RAW. (What did I expect? Garbage in/garbage out.) Though I tried my best to work with the new "RAW", I was better off working with the original JPEG and exporting that as a TIFF.