Flexi handles are fine and performance isn't really effected from brand to brand (though comfort may be).
Only time I can think performance may be compromised is if you had a largish kite that required a lot of brake to kill it and you were flying on short
handles - but that won't happen with Flexi handles or a 4m with any standard handles.
Depower Quiver: 14m Gin Eskimo, 10m Gin Eskimo III, 6m Gin Yeti, 4.5m Gin Yeti (custom bridle and mixer)
Fixed Bridle Quiver: MAC Bego 400, JOJO ET Instinct 2.5 & 5.5, Lil Devil 1.5, Sting 1.2
Rides: Ground Industries