I was trying to find a feature comparison for PaintShop Pro Ultimate and PhotoPaint, but was not able to find it. Is that a correct assumption that PaintShop offers much more features and flexibility for all kinds of tasks?
Yes but make sure you understand the core technology differences, PP - LAB, CMYK and spot color to mention a few, PSP does not support these required technologies, so work on files there and then take them to PP.
In my opinion the two programs compliment each other well, coordinate color management, use them each form their strong point and MAKE MONEY!