I use this: http://www.amazon.com/gp/product/B00HQ9CQ50/ref=oh_aui_search_detailpage?ie=UTF8&psc=1

I have had no issues with it, other than a small screw the I had to fix because it came lose from so much use.

Still don't see the need for an expensive focal reducer, it's not high tech gear.

I would suggest having both a focal reducer and a regular adapter so you can get twice as much out of your lenses.