Regarding the method of attaching a piece of butt section to the end of your line, tying a perfection loop in it and then looping your leader onto that:
I've used this approach on occasions when i've bought a new line and don't have time to wrap a good loop onto the end of it, and advise against it unless it is the difference between fishing and not fishing
On more than one occasion, while trying to break off a snag, i've had the mono at the loop-to-loop junction break. This is pretty remarkable to me, since the mono there was many times stronger than the tippet. My guess is that a braided mono loop on the end of the line is a better thing to loop to, since it is softer and not likely to stress the leader's loop.
Also, if you choose to go with the braided loops that you can buy in a package from cortland/orvis, don't rely on the heat shrink tubing to maintain the "chinese finger cuff" attachment. The heat shrink tubing works well to cover over the frayed end of the braided loop, and the braided loop will seem to be ready for a bluefin tuna. However, a little pressure in the wrong direction of the whole thing from your rod guides will cause it to slip off.
There are a couple of ways to deal with this, one is to coat the braided loop, especially including the heat shrink tubing, with aquaseal. I suggest dilute the aquaseal with cotoul (sp?) so that it can be smoothed out better, and work it into the braid with a business card or something, then smooth it off well so that it isn't too stiff or heavy when it dries.
For even more insurance, what i do is add a couple of lashings of 6lb mono, each approx. 3/8", right next to each other and right next to the heat shrink tubing, before coating the thing with aquaseal. I'm still waiting for a stray bluefin to come along and test the approach