I played a Hammond 10L for many years and preferred it over the Wick 4AL (which was my default mouthpiece at the time).
The 4AL sounds better down low, but feels really "lumpy" to play (some notes spoke better than others). The HD plays really smooth (consistent) throughout the whole range with a good clean sound, and sounds great up top.
I also had a 10XL but to me the 10L hit the sweet spot, and the 10XL was just more work for minimal gains. I also must declare that I prefer my sound warm, rather than dark.
I've since moved to the SM4U and then the SM3XR, for a sound that has more presence in a brass band.
Ted
Besson Prestige BE2052-8G-0 Euphonium
Besson Sovereign 956 Baritone