Longer lines create a bigger powerzone which may only be necessary if you are doing any traction activity. Longer lines also slow the response of the
kite.
Blades are typically flown on 25m lines. All my kites are on 25 or 30m lines.
I like the 30m for my 2.5 and sometimes my 7.0, but generally prefer 25m for all else.
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