I wouldn't call the hand compressors unsafe. They all have safety lock in there that unless you have no idea what you are doing, the worst you can do is get into an awkward position that is difficult to unwind.
But like doitmyself said, you need some basic mechanical skill to know what you are doing, or pause and look for help when something doesn't look right.
What I think could be a problem for backyard mechanics to do strut works is to rent tools during weekend (strut compressors are always out when you try to rent or borrow), some bolts may snaps especially in the rust/snow belt or up north, and sometimes the compressor won't fit the clearance when you try to put things back together (interference between a metal dust shield and the strut compressor, etc).
I would make sure a part car is around in an emergency, and do it on a Saturday instead of a Sunday. I personally had a quick run to a local Firestone to compress 1 of my 4 strut back together when my compressor won't clear the dust shield, and that's the 2nd car I did and have full confidence on what I was doing.
For most people who won't keep a car for another 10 years, I think Quickstrut is a decent idea and save you a lot of of headache. What I'm not too comfortable about Quickstrut is that it is a Monroe and they aren't as good as some other brands like Bilstein, KYB, or Tokico.