Not quite convincing is it, that 2nd Chamber Symphony? Sounds to me like "Schoenberg for those who don't like Schoenberg", one of those pieces such as Verklarte Nacht (masterpiece in itself of course), Berg's Violin Concerto may be another, which allows those who can't cope with the more radical languages of the 20th Century to think, wow, I can enjoy modern music! If that's old-fashioned R3 elitism then - tough!
Always been fond of Gerhard's 1st, a complex otherworldly epic which still has some traces of sonata-argument and shadows of conventional thematic outlines, I love the contrast between those and the innovative and fresh orchestral sound. It's a piece to get enjoyably lost in! The nocturnal slow movement, intensely atmospheric, can be rewardingly returned to even on its own.
But yes, all 4 are very distinct and worth anyone's time - lots of it.
Huge admirer of Simpson (as a student, I nervously approached him in the RFH Green Room just after his talk about Bruckner 7 - he looked stern, but was very welcoming and complained that Groves had taken 6 minutes too long in the premiere of his own 6th!)
Nos. 3 (that dolce clarinet solo recalling the opening string theme after an explosive finale at the end of 2nd movement (you might think of Nielsen 5(i)), and 5 (astounding motivic/intervallic integration allied to rugged dynamism) are especially fine... 9 probably his magnum opus, lovely extended slow movement in the Hammerklavier-like 10th too (remember the lovely pastoral landscape on the hyperion CD "The Cloud" by one Prince Eugene?)...
How we neglect our own treasures, I wonder if the BBC ever forgave Simpson for being bloody-minded (and usually right!) about many things... at the Green Room in 1981 he said he disagreed with Hans Keller a propos foregrounds/backgrounds, I'd asked him whether he saw Bruckner in those terms...
What about DSCH? The 10th and 11th develop broadly the same forms he used in 5 through 7, but then (drawing a veil over 12...) he takes a radically different direction in 13, 14 and 15, expressing the bitter truth about USSR's dark and death-haunted 20th Century history in completely new shapes.
Indeed the Soviet symphony after 1945 could be a whole thread in itself... Schnittke's 5th always impressed me as his most cogent, despite a less radical shape and sound than his later much stranger, offerings. He always finds intense veins of inspiration for slow movements q.v. 6 and 8, but the air they breathe is often from other planets...
Is there an echo in here?
I too am a wildly enthuiastic devotee of the music of Robert Simpson, and with the amazing Ninth Symphony we have on our hands one of the great 20th Century symphonic masterpieces: I was fortunate enough to make the first London performance of this astonishing work with the Philharmonia Orchestra conducted by Simon Rattle in the RFH, with the composer present, and it certainly packed a punch. I'd already become acquainted with Tod Handley's Bournemouth recording on Hyperion, but it was a delight to hear it live. Awesome is the word...and at 45 minutes it cannot be described as short.
It is a shame that more stuff by Doctor Bob does not get wider coverage, especially on the BBC, but then there are still elements with the portals of Broadcasting House that resent Simpson's valiant stand against the direction that music policy was taking, which of course led to his resignation from the Third in the 60s.
A truly wonderful genius.