I also have the Sage one linked above, and it’s great. Yes, it’s possible to get a puck out in other ways, but it’s very much a case of the right tool for the job – it just does what it’s designed for in a very effective and satisfying way. If you’ve paid a few hundred quid for a nice coffee machine, why put up with mess and faff that spoil the experience for the want of an extra £20? (And yes, I’m aware that’s very much in the first world problems category)
On the compost/gardening points, I did a fair bit of reading about this, with inconclusive results. After a few weeks of putting the broken-up pucks on the garden (around a hydrangea to see if the pH difference affected the colour of the flowers) I noticed the growing tips appeared “scorched” and stopped – not a scientific experiment by any means, but they just go in the food waste now.