pro's - bigger wind range, as stops kite " bending" in strong gusts and funneling wind to the center of kite, and smothens out the gusts slightly.

relaunch the kite without swimming while leaving your board on your feet in minimal time

ride with a leash and safety that's easy to use and to re-attatch in the water

cons - some 5th line producing companies havn't put a stopper on the 5th line... so when you engage your safety.. your bar will fly to your kite and create a BIG mess, aswell as nearly being impossible to relaunch in the water due to the tanglethe non stopper 5th line safety causes.... so make sure you get a stopper standard, or fit one that has been properly adjusted before hand.

yes you can wrap your kite up in the 5th line : when........ if there is no wind, is it possible for it to twist wierd ways when jellying / luffing or even on relaunch due to the low wind ammount, and not enough aerodynamics for the 5th line to take up the slack, and keep the kite in it's proper shape... It has happened to me.. and your kite will not rip in half if it does happen due to low wind.. just pull the 5th line in untill it unwraps.. If there is enough wind to kite upwind.. i have never had it wrap up, and the only other time it could happen is in the surf... and it could destroy your kite.. but surf destroys all kites, 5th line or not... atleast you have a faster chance of relaunching it with one attatched.....
also some people comment on having 5 lines out from your bar? if thats a problem you can allways run your front lines of a single line for 5 meters and then split it into two.. so you still have four lines at the bar... your best opinion will be after you've tried one

For me

Pros : Spinning leash, super quick relaunch, greater wind range, Rhino Vs don't fly without 'em.

Cons : Exponentially increases set up time, that additional line just seems to entangle so much more easily. Freaking out whenever I drop the kite in surf. (Yet to rip a kite though) North setup needs retrimming after a few sessions.

Bit of give and take really, I only find it a disadvantage off the water when I'm setting the kite up, other than that, it's all good.

Seting up 5 line is easy for me?

-keep your lines straight-unroll your lines the same way you rolled them up
-dont let your girl friend or anyone else roll up the bar.
-Unroll your bar, up wind of the kite so when sorting the lines all the tangles get blown down wind
-When you use it and play with it some more there is too many advantages to even consider using 4 lines again?