I can't comment on the eCoSoft runtime but I can tell you a bit about one of the add-ons that use it: PNG Desktop, aka Sunny Icons.
A few weeks ago, eCoSoft gave Arca Noae permission to have me create a customized version called "Dynamic Icons". Since then I've put in an enormous amount of time chasing down bugs and reworking its menus and notebook pages. I have to say that I'm extremely pleased with the results. The version I released yesterday (beta72 - sadly, only available to AN testers right now) is quite stable and, IMHO, easier to use. If you decide to install AOS when it's released, I hope you'll give it a try.
BTW... an AOS-only feature lets you turn customized icons on and off. If you install 3rd-party icons and find you don't like them, you can just turn them off and use expanded versions of the stock icons until you find a set you like.
Also, to follow up on a question that Martin asked a few months ago... It appears that XWP's Xview and PNG Desktop/Dynamic Icons are fundamentally incompatible. Sadly, most of that incompatibility is due to Xview's design. PNG Desktop was designed to support standard WPS folder windows: one folder per window with all of its settings stored as part of the folder object. In contrast, Xview displays multiple folders per window and stores its settings outside the object in os2.ini. Getting the two to mesh would probably take a lot of work.