I have a similar situation. I'm told what happens is.... (whether this is true or not... we'll see...) everything is taken off the devices and kept on a database. So while they DO destroy the physical device, they should keep ALL device contents on a server. That came from my first RMO who promised me he would look into getting my documents back as I have photos of relatives who have passed on there. I've since moved house (and police forces) and he's stopped replying to my emails... I'm tempted to ring and chase it up.
For what I know, legally, you are entitled to everything back that did not break any laws (Please correct me if I'm wrong). I fought for this from day one as they took a lot of my things. I kept the itinerary list of what they took on the day of the raid and, fair play to them, they returned everything to me that was 'clean' including a laptop, mobile phones etc.
I agree that the court deciding to destroy devices needs to be thought through again. In this day and age computers are more than just computers they're your 'record collection, family photo album, workstation' etc all sorts of things and they can't just be treated as a 'computer' and this needs to be taken into account with raids, holding of devices for investigation and the return of them afterwards.
As a side note, they took my girlfriend's devices too, but I (calmly) pushed to get those triaged and they were returned within a few months. I include that line in case this helps anyone else's situation as this was a big relief for her when I managed to get them back.
I have to say, the officer who I was dealing with was very professional and was very reasonable throughout. I hope they're all like that because I know how much of a stressful situation it all is. I do, however, think something should be done about the length of investigation - the mental impact it has on you and those around you is horrendous and mine went on for 14 MONTHS (From raid to court) not knowing when they are going to decide your fate for so long absolutely destroys you, it's mental abuse, and that isn't taken into account on any level.
Fighting or Accepting - its difficult to know which is right and when.