Tried out the narrow tubes tonight with the triple flange tips. Gotta say I like the sound of these too. I wouldn't say there's more bass, but the tonality is definitely different/darker. If you find the treble too bright or sibilant before, I highly recommend the narrow tubes with triple flange, no signs of sibilance at all and very good balance. Sound is slightly darker than neutral but still good treble detail and resolution.
The fit take a little to adjust and get used to. Similar to Etymotics with deep insertion. Had to angle them and twist into my ear in order to get a good fit, but once they're in they're pretty comfortable. Sound is more intimate and not as open as the wide nozzle. So soundstage sounds more like your typical closed IEM instead of semi open back. But the tuning is excellent and near perfect to my ideal tuning. Everything is so well balanced and nothing stands out over the other. No spikes or dips anywhere. Very fun and musical.
FD5 has become one of my favorite reference grade IEMs now. The ability to switch up the presentation is nice and it responds so well to different tips, cables, etc. An audiophile's dream! I'm eager to hear what the FD7's have to offer.
Edit: It handles acoustic music like a champ,
Jack Johnson's On and On sounds fantastic! Can't stop listening, I'm rediscovering this album on an intimate level.
Pink Floyd sounds great too. These make a good substitute for my full size Grado's.