I've continued to use Solid Explorer Beta2 and so far, with one exception, it seems to work well. The exception, as mentioned before, is that I can't connect to the root via FTP from PC. The advantage over ES is that it doesn't time-out. I rate both SE and ES well above File Expert.
Sprint Galaxy Siii Android 4.4.2 rooted RingPlus (Sprint)
gsm Galaxy Siii Android 4.4.2 rooted Cricket (AT&T)
Hisense Sero 7 Pro Android 4.4.4 (DoPa2.51) rooted