A discussion of the dangers of SEP IFR flying which concentrates on engine failure totally misses the true areas of risk in IFR flying.
Analyses vary, but typically mechanical failure accounts for less than 15% of fatal IFR accidents. Of those, about half of them will be vacuum and electric system failures, a quarter fuel exhaustion and a quarter mechanical engine failures. These proportions are roughly the same for both twins and singles. In the last analysis I read (Collins - Flying IFR) singles came out slightly more dangerous than twins for system failures, but significantly safer than piston twins for engine failures, even after adjusting for the higher proportion of twins flying IFR.
Krallu - if you're actually interested in evaluating and reducing the real risks involved in SEP IFR flying, I suggest you read a good analysis of the accident report statistics. Richard Collins has covered the question a number of times in his Flying magazine column. Alternatively there's a chapter in his book Flying IFR on the risks involved. The NTSB also publishes accident statistics - I believe they're at
http://www.ntsb.gov/Aviation/Stats.htm but the site is down at the moment.