I have no problem at all using Topaz Sharpen AI after DeepPRIME in PhotoLab. In Sharpen AI, I leave noise reduction at default, which tends to be low. The trick is to get the right kind and amount of sharpening and to decide whether or not to sharpen selectively using a mask. Watch what happens in blurred backgrounds, for example: DeepPRIME XD is best for bokeh - but where there’s a lot of grain left by PhotoLab, Topaz can smooth it out nicely. Too much sharpening (not noise reduction) will make a mess of things.
I often use Gigapixel and Sharpen on images that I have cropped in PL6. I have found that leaving the NR settings in these two programs at their defaults(very low after DPXD) and low sharpening settings(around 10) helps to mitigate the problem of over sharpening and produces very nice photos. With GPAI and SAI I can restore the cropped photo back to it’s original size or larger without incurring any over sharpening. Photo AI is not quite up to speed with GPAI and SAI yet but is getting better each week.