I find myself wishing I could just try a 4Z with my Hugo2, to see what the uptake is. But, I really can't complain about the X. You're right about the combo of X/H2.
Don't do it! Fair warning... For example yesterday I found some good bass test videos to use to verify my thinking about the bass response being a bit light on the 4z. Well I was thinking wrong. I listened to a few selections that plumbed the depths of bass then rapid-fire ran to upper-mids then massively dropped hard to under 20 Hz to mid-bass etc at some really robust volume. I was blown away at how the 4z handled this. That would have been pushing it with my X, but the 4z just stayed unbelievably tight and clean while going subterranean. Of course having the GLMk2 driving helped a lot no doubt but still... When there is bass, the 4z is gonna serve it it up steaming hot tight and clean. But the overall signature tends towards an incredibly accurate, more neutral presentation. And they will thrive on all the power fed to them too.
Color me impressed to say the least. These things rock. As does the whole chain really. Do I regret having bot the 4z? Not for one second.