Well, a boot manager should give it a pretty good boot rate I would think. I could send you my boot menu if you want to try it and see if it helps (I'm not thinking that should matter though). If you want 100% boot rate, you could install A9LH. There's a guide for that
here if you're interested. I don't know of any Spanish guides, but maybe Google Translate can assist you with it. It's not complicated, just takes time. And where he says "RedNAND" just think "EmuNAND" -- any type of EmuNAND will work. That said, Gateway does have a tool for A9LH coming out in 6 days (at least that's what their site says), if you don't mind waiting. It's supposed to simplify the process.