I always feel the need to add the friendly reminder to pay attention and be careful if you're opening one up to threads like this. The capacitors aren't critically hazardous in units that small, but they carry more than enough of a jolt to do rather unpleasant things to you if you short them out in the wrong way when they're fully charged.
The shock itself from flashes that small probably aren't going to kill you on their own, even if there is the potential for it to mess with your heart rate, but they can easily throw you off balance and stun you a bit.
Canon EOS 7D | EF 28 f/1.8 | EF 85 f/1.8 | EF 70-200 f/4L | EF-S 17-55 | Sigma 150-500
Flickr: Real-Luckless