doubletaper vs weight forward lines

 i never understood why a company selling a combo with a short rod 7'6" or so for small streams doesn't put doubletaper lines on the reels instead of weight forward. they have to know that the user will be doing a lot more roll casting and short casts and delicate presentations and from my experience doubletaper is the way to go. any one else have an opinion on this??
 i also use a dt line for my steelhead fishing because of all the roll casting anyone else do the same??
 
there are a lot of newbies getting into fly fishing and i'm sure this will help immensely

Being very new still, I will say this. It doesn't matter what line I have on what rod/reel combo. They're all going to suck at a rate proportional to my casting ability, which is very bad.
 
Lots of practice is what I need. If there wasn't such a nice stream so close by I would probably get it too!
 

I have a lot of different lines, both DT and WF. I use whichever casts best with the rod i'm using. I heard someone in a well known flyshop in state college tell someone that WF lines are superior in all ways to a DT line. That is absolute bull. Here in PA, and on most trout water, you NEVER need to cast 90ft to catch a trout. Heck, the vast majority of flyfishers cant even cast 90ft. Why then, would a WF line be necessary, or superior?
 
WF lines will cast further than a DT, that is a given. On the other hand, you get twice the life out of a DT. I guess it all comes down to personal choice.

  I'd think most people buying combo's are beginners.  WF is easier to learn with than DT.  It's also a more popular line.  Me personally, I don't own a singe WF. 

so from what you fellas say get the wf off my 5 weight and go to a good dt line as for casting i am ok i guess.

On the subject of roll casting, do you guys see any difference in rod weight and length? I have a 7'6" 4wt. medium/fast, and a 9' 5wt. medium.
 
I  have been practicing and using the 4 wt. on stream, but which would you guys recomend to develope some proficiency?
 

Gentlemen,
      Just my 2 cents! I prefer double taper lines for almost all fishing.  When it comes to roll casting, with a shorter rod you must develop more wrist/arm speed to get the weight of the rod and the rod tip moving fast enough to lift and move the line.  When I roll cast I try to make my last 1/3 of the cast much faster than the start to reduce the size of the loop.  In my experience, most trout are caught quite close to the fisherman and the need for long casts are overblown, unless you are fishing drys where there is a lot of pressure.  I once read that the old bamboo rod makers had a rule of thumb that if you had more than twice the rod length in line out (not counting leader) you had too much line out for the rod and were over stressing it.  (see mid and tip fractures)  And it's something I tell everyone I build a bamboo rod for.
      We have gone beyond this with our newer composite rods but I still feel it is a good rule to try to follow.  Ie:  a 9'6" rod could have approx 20 feet of line out and 9 foot of leader + 2 foot of tippett = 40 feet reach.  Not many people can control a fly accurately at much over that distance.  Yeah, it looks good on the videos but the reality is quite different.  Just look at the tribs.  with the exception of the bottom of ELK and maybe the wall there are few places where you need much more that 20 feet.
        So that means that a DT line, with its' better control, is best for this type of fishing.  There is very little use for wt fwd when you are also adding weight to get the fly down.  For drys maybe, but generally DT is better. 
      My advice to my new fly fishing friends is:  Practice till you can put your fly in a paper plate regularly, with about 15 feet of line, then keep moving back till you can't hit the plate very often, when you reach that range you have reached your level of competency and you should try to fish within this zone.  Your presentations will be better which will result in more hook-ups and much more fun.