Bigfoot,
I convinced my dad to buy a halfblood Simbrah bull back around 1983 (he wasn't black) to run on our little ragtag herd of crossbred cows back in south Alabama - cowherd was bred up from Hereford/Red Poll with some Jersey & Guernsey back behind some of them... with about 15 years of Angus bulls over them.
I have no idea what Simmental or Brahman lines were behind him, but he was EASY calving, and those Simbrah-cross calves were the best that I can ever recall us producing. Color was all over the place... but this was before the CAB marketing success, so 'black' didn't necessarily 'rule', and with only 1/4 Brahman influence, the dock for 'ear' wasn't too bad... and, really, for that part of the country, I think we'd been leaving a lot on the table by not having some Brahman influence earlier.
Haven't seen many in the interim, but most of the Simbrah bulls I've seen in the semen catalogs... just don't flick my trigger. As much as I like my Simmental cattle, and had a good experience with that Simbrah bull back when... I'm not sure you'll get more bang with one than with a Brangus bull.