Mine isn't hidden, per se, but by the time you get to it the odds are great I already have several pictures of who/what's going on.
I think you're missing the point made by the OP. When they get to it and take it or the internal HD, you no longer have any of those pics (unless you have working SD backup cards in your actual cameras, note the word working here), as your pictures and evidence go with the stolen pc / hard drive / nvr.
If you have the option then I'd say better to hide it than not.
I've been meaning to set up a permanent secondary recording solution as my PC/server just sits on the floor next to my sub and TV cabinet. In the meantime my setup automatically fires alerts for motion on my property to a gmail account. Even if a thief went the whole hog and cut my phone line the system has enough time to send snapshots and a video from multiple cameras.
My thoughts on a cheap system - using stuff I already have - would be a Raspberry Pi and portable SSD recording snapshots at 1fps.
I don't have an alarm because my wife would never set it and would complain every time got home before me and had to disarm it - she's from the land of high fences, bars on the windows and guard dogs behind your gate. Fortunately the area we live in is not wealthy enough to be targeted for break-ins but also not poor enough to have people hanging around causing trouble. The most action my external cameras usually get is letting me know when that damned cat is in my back garden so I can switch the sprinkler on.
Several alarms have wireless remote controls that allow you to arm / disarm them just like using a garage door opener or gate opener. Yes some might say this compromises security, however, the better ones have rolling code encryption. Is it 100% proof? I'm guessing no. But I've had one for more than 10 yrs and never had an attempt yet. Good door locks go some way to keeping them out and bright LED floods at night time.
As for not taking pc's, I think it probably depends where you live. They used to take pc's over here but not so much anymore, more cash and jewellery and sometimes tv's. It's also going to depend on your physical location within a country / town as to police response times. My neighbour was burgled and the guys doing the burglarising parked their getaway car at the bottom of the drive and walked up laughing and joking so loud, I heard them from inside my house through double glazing from a distance of around 150 feet.They calmly broke in, in full view, switched the lights on, and stole goods even standing at the now lit windows. They then got in the car at walking pace around 20 mins later and drove off. They weren't in the least bit of a hurry or cared who saw them. I'm pretty sure they were armed with several knives and at least 1 hammer (the break in tool) and were prepared to use them. I was straight onto the police before they even got in as I knew my neighbour was away, but on a dark night, out numbered 3:1 with no way to defend myself, plus I'd end up in jail over here for wielding any kind of weapon, I had little choice but to leave it to the police who unfortunately had the nearest car, quite a long way away and arrived just after they'd gone.
I can't give specific advice from my experience on what to do with the pc / nvr, but personally I never think it hurts to air on the cautious side as it's the only item that stands between them getting away and you recovering your items.
