Will have to agree with D.R. on this. In my opinion, Longhorns are no worse on fences, or anything else for that matter, than most breeds of cattle. You can get a wild Longhorn just as easy as you can any other breed. When that happens, it's time to cull. Don't keep animals that tear up fences, pens, etc.
I have only been involved with Longhorns for about a year now, and from what I have seen they seem to be pretty easy keepers. So far, no problems calving either. The only drawbacks I see are marketing, and the ease in working the cattle. The Longhorn market for the most part is a niche market; however, there is money to be made if you find the right buyers. As far as working the cattle. you will have to consider a different set-up than the avergae chute and headgate for working mature cows, because of the long horns.