i've read about this before, but still undecided whether to keep using it or not.
Ok, i did find my self in few situations where i had to quick release to the 5th, and it was great. But two times (over the period of two seasons), my 5th line snapped (near the bottom end). This happened when i was trying to relaunch using the 5th (i.e. when pulling the 5th to angle the kite which obviously applies some tension), and once on the beach when i was adjusting the depower on the 5th. Luckily i was still hooked in, so the kite didn't fly off, but if it happened after releasing to the 5th i would loose the kite and the kite could have injured bystanders. So my question is did this happen to anyone else, and if so, what's the point of the 5th line if you can't rely on it that it will stay attached to your kite.
Last night i didn't have the 5th (waiting for a replacement), so i attached the safety to the back line, and had to use that for the first time, and after the kite gracefuly depowered and dropped down (and it didn't even twist that much), i now don't see any difference when not using the 5th apart from having less lines to worry about. Also i'm speaking purely from the safety point of view.
Any expert advice / experiences here? thanks
depends what kind of kite you have.
On my old school c kites it is handy to have a 5th especially for relaunching, but the 5th doesn't fly with (much) tension and so doesn't (shouldn't) break.
If you have a kite that relaunches easy without 5th you could go without.
Hybrid kites use the 5th for trimming the kite not just relaunch. There is tension on the 5th. It is more prone to breaking. It happens.
With or without, just make sure you can relaunch your kite easy and land it safely.
I've been flying 5th line kites since I started in 2005 and don't think I'd go for a 4 line setup. I like knowing that my kite will completely depower, but stick with me on the 5th line. I fly North kites.
I've never heard of the 5th line breaking before, but then I probably release the safety about once per season, so it doesn't get much wear.
what is the 'safety' that people keep referiing to ? Are you talking about a release or leash perhaps ?
Hmmm... sumpin nort write their Lizo??
More info on kite etc pweez?
Going out on a limb though it sounds as though your 5th is not a full spec line (as in could be used for front/rear lines) and some lighter/less strong line that has been used. Possibly there is a burr or sharp edge chaffing the line somewhere though?
If it is an old C kite then definately stick with a new full spec 5th line for safety/re-launch etc. If you let go on the rear line, as described, of an old C kite and didn't get major spiralling/tangles then the winds were pretty light and you were most likely very lucky.
I'm flying 07 fuel. And last night was 20 - 25 knots, and when i crashed after a jump, somehow the chicken loop got disconnected, so the kite depowered onto the rear line, fell down, and didn't really spiral like crazy in the water... to which i was surprised as i've heard that they usual spiral.
My 5th line is the original manufacturer's line build for 07 Fuels. I do use the same bar and lines on my 17m Fuel few times a season during light wind days, so given that that's much bigger kite, perhaps it wore out the line. I don't know. I still expect something like this never to happen, and now i have doubts about it's reliability.
The '07 Fuel's have the clamcleat for below the bar trimming of the 5th right?
I was using that setup (not on a Fuel) a while back and also had the 5th line snap where it runs through the bar. If i recall the section that runs through the bar can be replaced separately to the rest of the 5th line... or atleast i know it can on my current Naish SHIFT (5-liner) setup.
I guess it's just a matter of keeping an eye on it and giving it a pull test once in a while. It's just a little hard to simulate the sorts of strains a 5th line gets put under whilst your binning a kite into the water at Mach-1 during a failed loop. 
thanks koma, i think that's exactly what happened. Yes, i do have the trimmer below the bar and that's where it snapped.
