[3] Critic Jason Ankeny describes Marshall as "one of the most distinctive and original saxophonists of the postwar era.

In May 2004, Allen celebrated his 80th birthday on stage with the Arkestra, as part of their performance at the Ninth Vision Festival in New York City.

Allen gave other performances on his birthday in 2008 at Sullivan Hall and at Iridium Jazz Club in 2018, both in New York City.

Allen often appeared in New York-area collaborations with bassist Henry Grimes and has also participated in the "Innerzone Orchestra" together with Francisco Mora Catlett, Carl Craig and others in an appreciation of Sun Ra's music.

[10] On October 4, 2024, he released the first single "African Sunset" from his forthcoming debut album as a solo artist which was recorded a few days after his 100th birthday.