Rumpelstiltskin, CBSO Centre, Birmingham <br/>Swanhunter, Howard Assembly Room, Leeds

Commissioned by Birmingham Contemporary Music Group, Rumpelstiltskin is the third of David Sawer's works to explore greed. In From Morning to Midnight (2001), Georg Kaiser's bored bank-clerk unravelled to the accompaniment of whirring bicycle wheels, buzzing flies and vomiting prostitutes.

In Skin Deep (2009), the pursuit of wealth and beauty was played out over smarting strings and B-movie glissandi. In Rumpelstiltskin, Sawer's score is a rich broth of Petrushka-esque carnival music, Depression-era dance music and melancholy doynas, with 13 instruments providing the voices of the silent actors. It's a work that is hard to categorise, neither dance nor opera, but storytelling through music and movement.

With shades of Erich von Stroheim's silent film classic Greed in the lighting designs of Mimi Jordan Sherin, Richard Jones's tart, sharp production has Rumpelstiltskin (Sarah Fahie) as a tiny, gold-toothed vagabond. Crippled by debt and drink, the miller (Chris Harrison-Kerr) is hiding from two bailiffs whose pacing feet set the rhythm of the opening dance for double-bass, bassoon and tuba. Muted trumpet and horn announce the distraint of table, chair, even a cobweb, and, in one fantastical, desperate lie, the miller consigns his daughter (Bryony Perkins) to spin straw into gold for the king (Nicholas Lawson). Imprisoned in the wooden box that is Stewart Laing's set, Perkins weeps to a quartet of violin, viola, cello and harp (the players painted, like the actors, with the monochrome cosmetics of early cinema). Pale pizzicato figures cast a chilly spell as the box slides shut and Rumpelstiltskin sets to work, his fee the first-born child of the girl.

From the ever-darkening timbre of the alchemy music to the expansive horn solo, the brittle, syncopated wedding music, mocking flute and stuttering speech-rhythms, Sawer tightens his score with unerring focus and is handsomely served by BCMG's virtuosic instrumentalists and conductor Martyn Brabbins.

Children more familiar with the Mario brothers than the Brothers Grimm may be startled by the economy of Jones's imagery, the directness of expression from the cast, and the black comedy of the grisly dénouement. Though it seems unlikely that Rumpelstiltskin's moral will register in the run-up to Christmas, its fidget-foiling duration of 70 minutes should not alarm the Nintendo generation. Anyone near Huddersfield should try to catch tonight's last performance.

Scored for six singers and as many instrumentalists, Jonathan Dove's latest opera is also pitched to a family audience. Where his previous Opera North commission Pinocchio sprawled across three hours without so much as a memorable tune, Swanhunter is succinct and catchy, with a cantering motif for accordion (Murray Grainger) and a witty libretto adapted from The Kalevala by Alasdair Middleton.

With Andrew Rees as Lemminkäinen and Yvonne Howard as his mother, Elizabeth Cragg, Frances Bourne, Nicholas Sharrat and Graeme Broadbent relate (and comment on) the impulsive hero's quest for a bride in sweetly-blended two-, three- and four-part harmony. Dove's musical language is unfussy and efficient: the splintered ice of the extreme North is conveyed in sparkling tuned percussion, a horn neighs violently at the appearance of The Devil's Horse, and the Swan glides to Cragg's stratospheric vocalise. Excellent ensemble-work aside, the vocal honours go to Howard, whose anxious refrain is expanded into a grand lament as she journeys to the north to reclaim her "cold, torn" son's corpse.

Designed by Dody Nash, Clare Whistler's athletic touring production has some ingenious touches. The hooves and antlers of Death's Elk are garden spades and shears, Lemminkäinen's home a fairytale turret, the ice-floes smoothly-curved abstract shapes, the costumes cosy padded parkas. At times, the jovial, credit-crunch atmosphere feels like a community theatre workshop in a garden centre, and I wonder if children might not feel a little patronised. Swanhunter and Rumpelstiltskin are both intriguing introductions to music theatre but were Sawer's cautionary tale and Dove's Finnish adventure to clash, I know which I'd choose.

'Rumpelstiltskin': Huddersfield Contemporary Music Festival (01484 430528) 7pm today. 'Swanhunter': Howard Assembly Room, Leeds (0844 848 2727) 3pm/6.30pm today, then touring