Responding for myself, I have been enjoying the Sinopoli 2nd VS set, it's certainly not run-of-the-mill! Sinopoli puts a lot os passion into the music, so it can sound quite turbulent and quite exciting/excited. Gurrelieder is very good here, but I reckon his approach (a bit like Karajan, without the "lush perfection" (sic)) works best in the Berg pieces, and he gives the Webern pieces a different kind of liveliness than many others I have heard. Romantic Webern? Well ok, not necessarily the authentic approach! But it works fine, even if it underplays the revolutionary aspects of the music of all three composers. I didn't enjoy many of the other vocal works, beyond Gurrelieder. Odd balances, woolly words....
Gielen on the other hand makes every detail really clear, without sounding like he's involved in a public autopsy of the music. And yet this is properly human music, it's primarily concerned with human emotions and humanity in general, this is definitely not underplayed by him, something I'd occasionally suspect Boulez of trying to do....