As longchuck say's ubbi, its all down to what each individual angler can manage and the kit they're using(rod length/strength).
I'd say the size of the river and maybe the type of pools/streams will pay a larger part.
Long lengths of line take greater skill from the user to handle and cast, they'll take a little longer to settle out in the flow and are much more easily affected by currents twixt the angler and the flee.However by and large once they're down and in, there's less tendency to lift in the current and will continue to find depth as the line comes round onto the dangle.Long lines will be better handled by longer rods of the more traditional action such as Hardy and B+W.
Shorter "Scandi" type of heads(hate that term, they're shooting heads!) are easier handled and cast, there's a far far greater choice of sink rates, style's and multi density lines.
Now once they're cast out, usually they find depth a bit quicker, they'll be less influenced by currents twixt angler and flee and will fish round slightly slower due to a thinner running line not catching currents as much and they can rise in the water a little as you come to the dangle.I find it's just a little easier to control sinking heads on the swing too as you can handline or lift the running line clear of the water to slow swinging progress.I also find it easier to pick a head that may well be a bit heavy to solely fish the far side of a pool run at depth, and strip back through maybe less productive water on my side of the river.
Now I'm a fan of sinking tips, as in the 15ft multi tip variety, coupled to a poly. as well it can give 25ft of sinker off a floater.I like the way this lash up fishes, I can get depth quicker, mend when needed, but by and large the line will fish round a touch quicker, can be encouraged to sink quicker initially and rises a little towards the dangle.
Now a contradiction in that I'm not really a Skagit fan, for purely personal reasons in that I feel they can fish too fast and offer too much resistance to taking fish(Grilse can drop a flee like a hot poker if they get alarmed by the heavy weight of a short fat Skagit!) and I don't like to fish tips that are short and very heavy as they tend to fish at a steep angle off the floating line.
For almost all my sinking set ups I am looking for a nice graduated slope from the surface to the flee, I don't want yards and yards of line down and in amongst any fish, rather than the flee and maybe the very tip section of the set up.It offers more direct contact that way and leads to less foul hooking and is less likely to scare fish by passing amongst them.
Now the only way I'd change that set up is if I'm fishing smaller pools on smaller rivers where space is restricted and the flee needs to be in and down quickly, I 'd still choose a sink tip of sorts, but maybe a heavier shorter quicker sinking tip that I could control easier over a shorter swing.
Nor do I like super heavy flee's either, preferring a flee that matches the line in sink rate and fishes as attractively as possible.
If you read between the lines you may well get the flavour a multi density shooting head of the appropriate sink rate to get my flee down where it needs to be(not allways dredging bottom!) is my preferred choice?, well you'd be spot on!.
My credentials?, well I started in the days of long rods and DT sinkers(now that was hard work!), progressing through Spey profile lines and now into the modern heads from shorter faster rods.The latter is deffo the easier option!, but as ever a little experimentation for where you fish is no bad thing, try a few approaches and see which "Suits You Sir" and your fishing.I'm perfectly happy with a Dual Density sinking head and a 10ft poly, or a 3D head and poly, gives me what I want and is pleasant to fish for a full day.
But ! and here's the rub, its not all about how deep, its the speed of the swing and where the flee is fishing best across your swing,regardles of sink rate, the flee and line will take time to get to depth and begin to fish effectively, thats the part of the equation that needs a little thought!.
Best of luck, Pedro.
Thanks Pedro, all you said is faultless. Short scandi lines in effect reach the depth faster than longer shooting heads and of course than long belly spey lines..i think the longer lines fish better in large pools where there is the need of a large swing, and as you said they mantain the depth better than shorter scandi lines ...and of course it depends always of the pool we are fishing..
Thanks again for sharing your thoughts..
Tight lines !!
Great reply Rennie, spot on. I am using sinking lines more and more now especially with light lies or plastic tubes as these will fish at the same depth as the line so long as you have current, lighter flies also have more movement as well. Due to the availability of sort head lines they are also great off switch and single hand rods. Last year I was on the Skjern and was using I/S5/S6 with a type 8 poly on the end on my 12'6", a joy to cast but it was also fishing really deep. I am old enough to remember using full sinkers like Wet Cell 2's, horrible things on a salmon rod.
I think the best sinking lines now are the muti tip versions that have slowly crept onto the market, for me in a sinking line the next cast zone is unbeatable, they are double density bodies to which you add an appropriate 15 foot multi tip type tip to the end, the option of changing the front section on a sinking line is a fantastic one, as it offers so many options in speed and depth they are only about 40 foot the tip but for me that's the sweet spot for for most 13 to 15 foot rods, shorter lines offer quite a few practicable advantages like salmologic and guideline compact on smaller rivers, but I dont like them for the bigger rivers i fish