In my opinion, it's probably a little easiser now to sneak into a breed or reserve breed champion now than it used to be just because there are more good calves now to be had. However, if you want to play hard in the exotic breeds, you almost have to have a really good throw-away, old steer that more often than not will run out of gas before the majors.
A long time ago, the Belt Buckle champions had quite a record of going on and winning Grand or Reserve overall at one of the majors (i.e. Brandon Horn's shorthorn from way back, Vicki Priesmeier's Woody steer (still my favorite single steer of all time), and several others (Rash's, Jeffries, etc). It's not that way any more.