Thing is, I tend to use my 6 wt fly rod for both trout fishing as well as steelhead. I use either 3x or 6x leader and I hate alternative between leaders by cutting and retying a nail knot. Could I connect the two with a loop in loop knot? If so, do I use a double surgeon's loop? I tied it once before, but I don't know exactly how strong this knot is, but I like how I can change leaders very quickly without actually tying a knot. If I do tie a loop in loop knot, will the casting be affected at all? is there any disadvantages to the loop in loop knot?

also, I see these devices for connecting the fly line to the leader, how are those?