I use acme on a daily basis for Real Work™. Previously, I was an Emacs junkie, but upgrading el-get caused me grief for the last time.
I haven't heard of anything about "modern" acme clones, but I've actually found acme as-is from p9p to be palatable on a MacBook Pro. There's one chord that I've found to be nigh on impossible to sort out (for those keeping track at home, the 2-1 "execute with argument" chord), but I find that I don't really use that one a whole lot anyway.
On Linux, YMMV, but I've noticed that it's more than usable on a ThinkPad with the standard fare TrackPoint pointing device, at least once you disable, e.g., Canonical's emulation of middle-button scrolling as you'd find it on Windows. Once you get past that, it's swell, and all of the chords are accessible.
As far as some of the "unfeatures" concerns go, taking note that I'm not a Plan 9 zealot but a disciple of the Unix way of small, composable programs that all do one thing and one thing well, I can understand why something like syntax highlighting would be labeled an unfeature. Acme only provides an editing surface and a way to make text active; the rest of the functionality is provided by the myriad little programs that you likely already have installed.
Syntax highlighting would have to be provided in some form by an external program, and if such a feature were to be implemented, the community would want it done right and in the spirit of Plan 9 and Unix.
To play devil's advocate for a moment: ANSI (or some other encoding for this information) would be a suggestion, but then the concerns would likely arise about hiding information behind the text, which has been given some degree of meaning outside of merely being something painted to the display. Or, perhaps, someone would ask why there's a half-cocked reimplementation of drawterm suggested being embedded in acme.
I'm sure you'll find that a lot of people would not be opposed to seeing syntax highlighting and on-the-fly indenting and similar enhancements make their way into acme. The detractors will likely oppose the additions on the grounds that it may make acme more monolithic, depending on how each embellishment is written into the editor.