I had one that i ran until last week. I went into a ditch type thing and smacked my spare 33 and bent the carrier so bad that i couldnt shut it. I never had any problems with the weight thing. I also had my high lift mounted to it also.

I would vote for roof rack personally but then you have to think about the top heavy issue. Thing about the roof rack is you can pack all the fluffy stuff up there and then put the spare in the back.