I don't know anything about low-drop (or even what that means), but I have narrow, low-volume feet and was fitted in Vasque Blur trail-running shoes at REI. I use the Green Superfeet in them, and they work really well for me. They are not a narrow size but run narrower than other trail-runners, so said the fitter. Don't know if you've tried them or if they are even made anymore (mine are 2-3 years old), but I've been really happy with these shoes. Wear them for running, walking, and hiking.
Emily
2011 Jamis Dakar XC "Toto" - Selle Italia Ldy Gel Flow
2007 Trek Pilot 5.0 WSD "Gloria" - Selle Italia Diva Gel Flow
2004 Bike Friday Petite Pocket Crusoe - Selle Italia Diva Gel Flow