Valve Trombone attack or just the player?

[Gary]

I love Raul de Sousa on valve trombone except there's something about his attacks that bother me and I'm not sure if they come from the musician or the horn, itself. Perhaps some of you know.

If you listen to an average slide trombone and contrast it with Raul's, there's something different in the attack I hear. Word fail, but with the valve bone, Raul's attack seems a little, well for want of a better word, crude.

Is there anyone here who has the same reaction and, if so, would know if that attack is characteristic of a valve-trombone, itself, or just Raul? Thanks a lot.

[FullPedalTrombonist]

https://youtu.be/JZ2JdAG9hAo

https://youtu.be/IvmoeAcAIPM

Here are two videos from the same performance: one with slide one with valves. Different horns, but same player. I can hear the difference between the horns of course, but they both sound like him.

[Gary]

At first, I thought he might be using a softer, more legato tongue on the slide trombone, but I'm not sure why he would do that. Perhaps it's the horn difference?