8, the Midsummer Nights Dream one is stunning, and 6 or 7 I think uses electronics very cannily. The earlier
ones are on the expressionist/ serial side. Dennis Russell Davies in(?) Stuttgart I think, not certain, has done a
few and is good with linear clarity therabouts imho. I hadnt realise HWH had made it to 10-clearly having an Indian Summer compositionally.

I like Henze's early symphonies. I'm afraid I think he wrote too much later on, and became less self -critcal when it became clear everything he wrote would get a good performance.

I've never been able to listen to his operas , which many may think are his chief works. I try sometimes,but after a few minutes I start wishing I were doing something else.

Unfoprtunately they are the only performances of these symphonies I have  heard, so I  can't compare them with any others.But they have had good reviews and I enjoy them. Nos.1 to 5 were,I believe made from live performaneces in the 1960s. All I can say is they sound fine to me,and the recordings have aged well. .

I wouldn't hesitate if I were you, t_i_n. The recordings are excellent for their time, and the performances too, especially the 6th which is considerably more complex in texture than the ones before it.  Nos. 3 and 4 are also important pieces for me.

As luck would have it, this afternoon I was sauntering past a s/h shop I'd never seen before and, after the habitual but increasingly quixotic search for the Bamert Gerhard 4th, I happened upon a new copy of Henze's Requiem for 9 euros. I've never heard it before, having more or less lost interest in Henze at the time it was first performed and released, but from the first few movements it sounds quite impressive. Tristan is a fascinating work indeed, but for me it doesn't come near the Second Piano Concerto, which I almost always find a shattering experience.

There's actually quite a lot of good Henze. People don't talk about him too much because he doesn't fit well into any coherent idea of history (which is to his credit, but doesn't do him any favors). I am very impressed with his choral setting of Edward Bond poetry called Orpheus behind the wire. It was performed by the New York Virtuoso Singers on an interesting CD entitled 'To Orpheus'. Should still be in print.

I found the Requiem to be a little desultory, like the 4th Symphony, but I do like the 2nd, 5th, and 7th Symphonies fairly well. One can certainly learn a lot from looking at them closely. Also the Barcarola for Orchestra or the opera Das verratene Meer, based on Yukio Mishima's novel.

And let's not forget Voices, well, most of it anyway, and El Cimarrón, and the Cantata della fiaba estrema and Natascha Ungeheuer.

I much prefer the 4th Symphony to the 7th (haven't heard the more recent ones though).

One to avoid is Undine, which sounds to me like tired pastiche from start to finish.