VORTIME
There was a debate about engine failure rates a few months ago, resulting in a couple or more threads.
As Tomcs says, it is very difficult to derive any meaningful stats.
Other variables include QA/QC standards of manufacturing and maintenance.
The basic equation you have to consider is probability (difficult to define) versus severity (calculate for your self) versus the proximity window (i.e. how long are you exposed to the risk for.)
Ultimately it all comes down to your perception/tolerance of risk and there are 3 classic strategies for dealing with risks:
1 - avoid (decide it's too dangerous)
2 - mitigate (buy ELT, dinghy, wear lifevest, file flight plan) etc
3 - accept (take a view that it's unlikely to happen to you)
You might wish to search the subject on PPrune, as there were a number of anecdotal comments from those who have and have not experienced engine problems, that may help you to take this view.