DBChopper, I am surprised that your training school didn't expose you to downwind operations during the course of your training. It is good to see you are trying to learn more and erring on the side of safety with regard to them. I would recommend that you book in with an experienced instructor and do some.
Considerations with downwind approaches:
Only do them when you have to.
Make sure you are not out of your depth for your level of experience.
You must have HOGE power available.
Prioritise your potential hazards. Of course you should have a planned course of action should the engine fail as PPRUNE FAN #1 mentioned. However, the chances of the engine failing are extremely remote compared to you putting it into a vortex ring state or overpitching it due to insufficient power available. It is not much good finding yourself in VRS because you have flown a downwind profile to suit the remote possibility of an engine failure.
The R22 flight manual stipulates hover controllability has been demonstrated up to 17KTS from any direction. (This may have legal/insurance implications should something go wrong above 17KT)
The technique I used to teach was this:
Is it the only way?
Do a power check to ensure you have sufficient power available.
Make your approach angle on the shallower side of normal to ensure your ROD during the approach is manageable, and definitely no more than what you would have during a normal approach.
Keep the GROUNDSPEED during the approach comfortable and slightly slower than what you would have during a normal approach.
Regularly assess your airspeed versus your groundspeed during the approach, to determine if the downwind component is excessive AND to anticipate the loss of translational lift. Be aware that as you come out of translational lift the aircraft will want to sink out, and that sink if you let it happen may be all that it takes to bring about the onset of VRS. Anticipate the sink and don't let it happen.
If at any stage it feels too fast or doesn't feel right, initiate maximum power and go around.
I don't think downwind approaches are "extremely risky" or always unsafe as PPRUNE FAN#1 describes. Provided you are:
Not operating the aircraft beyond its limits,
Not beyond your own personal limits and level of experience,
Aware of the potential risks and how to avoid them.
You should be able to safely do one if you need to.