I waited way too long to try this out because I procrastinate far too much. I gave up fast on trying to dig into Potato and MUSHClient, not because they're bad or anything, but because I just wasn't getting things intuitively when it came to certain triggers and trying to set stuff up the way I was familiar with.
Aside from a couple minor differences (like how to set an idle timer, which I saw someone mention previously here), BeipMU feels so much like a successor to SimpleMU that it was a much easier transition. In fact, it's made some of the things I liked setting up for display purposes even simpler and I know I'm barely scratching the surface of its functionality.
Having the expanded color palette that's become more commonplace today is nice to finally get to fully experience, the ease of how the links work is convenient, and overall it just looks and runs more smoothly. Wish I hadn't waited so long to finally give it a try, but someone else was discussing it on a game recently and I figured I'd ask a couple questions then finally jump in. After a little trial and error and some digging deeper into helpfiles for one or two things, it's already sent SimpleMU into retirement.
Nice program!