I just tried Directory Opus 4.17pre21 (versions itself as pre20, though?) and it corrects a number of complaints I have had about DOpus 4.12 (which also began crashing on my 4000/060 recently for no apparent reason.) I also downloaded and tried Class Action -- it will take me a while, I think, but I think I can transition from DOpus (the biggest delay will be converting my pain-stakingly hand-crafted classes, whever necessary.) And it's great to see a newer version of FTPmount, LOVE IT!
In addition, I downloaded the latest version of IconBeFast from AmiNet. HOLY COW this is an excellent patch. I changed my icons to the AbandonMI set downloaded from OS4 Depot a couple of weeks back. They're REALLY nice but take a long time to load (reminds me of a slow Windows ME machine.) With IconBeFast they seem to just pop up instantly. GREAT job on this program!
And speaking of icons, PNG icons are fantastic. If you're interested in making some for yourself, I found that The GIMP 2.2 for Windows (and presumably Linux and Solaris) does a great job of editing pictures (especially removing backgrounds) and making proper PNG images which PowerIcons easily converts to icons.
At some point I think I will create a clean load of OS3.9 on my 4000 (need to clean out some decade-old libraries, dontchya know!) and put all these utilities in a scratch-bare system.* I started this thread with the intention of putting together a list of well-received and recommended utilities, and I think everyone has made that happen. Thanks to all, and I hope more will share their experiences.
* - My Amiga 4000 is actually the end-of-the-line for a system which started out on Workbench 1.3. It was upgraded to 2.04, 3.0 (warezed, sorry!,) 3.1, 3.5, then 3.9. Sure is a mess, but the system runs spectacularly.
Amiga -- I think even my girlfriend "gets it" :-)