I don't know if you aren't understanding me due to a language thing or what.
I have a 1,1 here and I was THRILLED to have a flashed 7950 as it's card.
You get full boot screens, perfect 10.9.1 performance, and a good Windows gaming machine, all in one.
The boot screens make switching OS's painless and worry free.
Right this moment I can hear someone in the office using it for "League of Legends"
A flashed 7950/70 and a 1,1 with Tiamo's boot EFI runs 10.9 just like a 5,1. Yes it is true you could use a GTX780 (better be sure it's an "A") or a Titan or a GTX680 or whatever, but any of those Nvidia options will NEVER have boot screens. The 7950/70 option gives you full, 100% seamless operation.
When 7950/70 first got released for Mac I complained much that the EBC boot screens gave impression that 1,1 had a savior, but lack of 32 bit drivers ruined it. Tiamo fixed the issue . Better than most hacks in most regards. No cost, nearly seamless. Doesn't really get better than this.
You can flash a GTX680 with "EVGA GTX680 Mac Edition"-ROM and you'll have boot screens as well.