Ask an Aran thread.

low HP is made up by how fast they gain it back with drain
stun/seduce is made up by body pressure keeping up the combo everytime you get hit

the only boss they cant combo is pap because of its "time out"

Well, I'm lvl 81, and I wish I had more hp. My hp is like 3,7k. Kents do 1400 damage. That means I have to pot every 2 hits, using a 2000hp pot. That means I pot very often, and with KMS delay (even with autopot), it slows my attacking a lot. If I had like 6k hp, I could use cheese, so I'd pot less often, and I could rely in drain more.

Body pressure doesn't always help with combo. If you are stunned after you "bodypressured" monsters, you won't touch them; so you'll lose combo..

And doesn't body pressure only apply to touch damage?

If you mean body pressure effect; no, you cause the effect with any attack. If you mean body pressure not-hurting-you effect, yes, only applies to monsters' touch damage.