I'm taking a long hard look at the various 85mm 1.4 lenses available and thinking that I want one, mostly for shots of the kid at his karate tournaments and other low light events. I think the 85mm focal length will be ok, especially compared to the 50 I use right now.

However I have a chance to buy a pristine 85mm 1.8D for less than 200 canuck bucks, and I'm sorely tempted.

So, looking for words from people who own, or have owned, either or both. Is the 1.4 really worth the extra in terms of IQ and sharpness? Or is the 1.8 probably all I'll ever really need?