Recently I was told by a rancher that I respect that their first Encore calves were very impressive. They used him for the first time a couple years ago on the advice of another highly respected, commercially focused rancher in MT. The calves are born easily, moderate framed, plenty of muscle, and decent growth.
Following are a few comments regarding some of the cattle that tncattle mentioned:
Atlas: great EPDs but phenotypically some of the calves lack overall thickness. Not only that but in recent years as some of the early Atlas progeny have aged there are many reports of cork-screw rear feet. That is a tough defect to breed away from so my suggestion is to avoid Atlas...wish I had 6 years ago.
Echo: Pretty cattle, but he will throw some white on the legs, underline, etc. Don't know if that is a concern for you. I never used him but have heard mixed thoughts on his cattle. He was used mostly by the show crowd.
Extra Exposure: Have only one daughter so can't say much about him. He has a reputation for siring good females (at least that is what his breeder Judd Ranch promotes). I see this bull also being used more by the show crowd than the more commercially focused Gelbvieh producers. I don't know if that means he didn't work for the commercial focused producers or they simply didn't use him much.
Never used Boo Boo either, but a cattle producer that I respect (Paul Bennett at Knoll Cress Farms in VA) used him for a year as a clean-up bull, when Boo Boo was fairly young. The comment that stuck in my mind about the bull's progeny is that they tended to be a bit "pencil-gutted." So based on Paul's comment I would only breed him to females with lots of guts.
The ABS bull that I have had good luck with is Carolina Rock'n. He is only 1/2 Gelb and 1/2 Ang but the calves come easily, grow well, and have some thickness.