Debate: “They were never the same after…” What’s the most seismic line-up change in prog history?

Only a handful of bands have retained the same line-up from beginning to end. For everyone else, personnel changes are a fact of life.

Artistic chemistry is perhaps the easiest part of the puzzle. Finding someone you can live with, in the studio and on tour, potentially for decades, is much harder to deal with. Then, of course, real life can and will throw curveballs, leading to a new round of “musical differences” that caused the previous line-up change.

Such changes can often result in a business-as-usual situation. But others are seismic for a band and their output – and future. Some groups never look back after restructuring with new chemistry; others are left wondering what might have been.

In the progosphere, Yes may be the first band who come to mind when thinking about revolving doors of membership. Would it be fair to say that the addition of Steve Howe is the most successful line-up change of the group’s history? Is the loss of Jon Anderson their worst personnel change?

What about Steve Hogarth replacing Fish in Marillion? Or Syd Barrett’s removal from Pink Floyd, to be replaced by David Gilmour? Martin Barre’s arrival in Jethro Tull? The shuffle that placed Phil Collins at the front of Genesis after Peter Gabriel’s departure?

In more recent years, Mike Portnoy left then returned to Dream Theater while Daniel Tompkins vanished then reappeared in TesseracT.

But there was no reversing the meltdown that saw Roger Waters splitting with Pink Floyd or Geoff Tate breaking up with Queensryche.

What do you think is the best-ever line-up change in prog? What’s the worst? And, importantly, why? Let us know what you think in the comments section below.