Why? Literally, every reason is a huge bonus compared to not using a hand-crafted European nymphing leader. The leader is specifically designed for maximizing your nymphing for strikes and feeling takes.
Overall, here are a few great reasons why you should be using a euro nymphing leader versus a traditional tapered leader.
Increased Hook-Ups
This belief is a little deceiving because European leaders do help you catch more fish, but it is more than likely your ability to feel every little take compared to before. You could have missed 5 out of 10 hits on a traditional leader modified for nymphing compared to 9 out of 10 on the euro rig. The thickness of the line used in the euro rig is much thinner and much more sensitive to movement and strikes.
Faster Sink Rate
Because a European nymphing line is inherently thinner by design, they do not have as much drag or resistance when moving through the water. Therefore, your nymphs are restricted less and sink faster against the current. Another benefit of line thickness is that the presentation is more natural and drifts freely within the current rather than being unnaturally stiff.
Easier To See With Sight Indicator
While Euro nymphing leaders provide more sensitivity to the point where you can literally feel the nymph dragging, banging against the bottom, and every strike, your ability to see in low and bright light situations only increases your chances. Euro nymphing leaders, typically, have a section of neon green and neon red built into the lower section of the leader. This provides a distinguishable indicator for strikes when the line goes from having a small amount of slack to a tight, resisting line.
Tippet Rings Make Changing Line Fast
We usually add a section of fluorocarbon as the tippet to tie our nymphs to extending from the smooth edges of the tippet ring. In our worst-case scenario, snagging on something and needing to snap it off, we can be back to fishing within a minute or two after tying new sections on and a new set of flies. Otherwise, we can quickly switch out flies or entire rigs with a simple clinch knot to the ring.
Cons To Consider
Euro nymphing rigs are prohibited over a certain leader length in the artificial fly-only sections -- depending on the state and local regulations. In many cases, commissioners have taken out a measuring tape to measure leaders if they feel it may be too comparable to monofilament conventional tackle lines.
Additionally, euro nymphing leaders are more difficult to cast as the thickness and stiffness of lines you’re used to fishing will not be present. However, this is by design as tight-line nymphing is not meant to reach more than 2x your fly rod length. With euro nymphing leaders, you’re largely swinging the weight of your flies and relying less on the weight of your line to cast.
Conclusion
With all things considered, you’re leaving a lot of room for improvement on the table when you’re not fishing a euro leader. You will dramatically notice the difference in your sensitivity to strikes, dings, and bumps below the surface. Personally, I carry two reels at all times in my pack -- one with a euro leader on the spool for nymphs and one with a normal tapered leader for everything else.