I have been driving 30 years and never heard of anyone doing this.
A neighbor has same XJ as me and put snows just on rear wheels. He says drives fine in regular weather and great in snow.

 

Nope. Doesn't make sense that it would work unless all you ever do is accelerate in a straight line.

 

Crazy. I drove for 30 years, 15 of those in the Bavarian mountains in the snow. Simply crazy. Get 4 tires for heaven sake.
Yes, when I was poor and drove junk cars I did that because I didn't have money. But please......we are talking about a $80k or $90k car not my $ 500.-- Italian junk car I had back then.

 

seen it a couple times, some people are just cheap. it works ok for traction from a stop but turning is still crappy.