The first time he did Beyond, we had just moved overseas, and because of our situation and family dynamic at that time (homeschooling a highschooler, the two boys, and keeping up with a toddler with special needs), not to mention the simple logistics of living in a foreign country (there was sooo much to see!), he wound up doing the right side of Beyond and just listening in on his brother's left side of Preparing. So the next year, we repeated Beyond with him, doing both sides. This year, my dh wanted the boys to study American history together, so I pulled my own thing together, and while we used some of the resources from Bigger, we didn't have the TM, so I know it would be a totally different experience next year. Part of me feels like I would be holding him back. He *should have done Bigger this year, so next year should be his year for Preparing. And we all really loved our year with Preparing and were really looking forward to doing it again.
But I'm concerned about some of the skills in Preparing. He is dyslexic (and would be doing Preparing a year earlier than his brother who is also dyslexic did it--AND he doesn't seem to be, um, conquering his dyslexic issues at the pace as his brother did--which is fine--it just affects his skill level). He is stuck about halfway through the ERS. I don't know his actual reading level, but I am certain that he can not read the science section independently. He loves science, though, and has done science notebooking this year, but only one or two sentences at a time and an illustration. I know that he will not be able to read the independent history section either. Now, with his brother, I read those boxes to him for the first several units, then he read them aloud to me, then he read them independently. I could try that with Josh, but I can tell that he is on a different level than Caleb was in Preparing, so I'm not certain it would work. I think I might be stuck reading them to him all year, which would not only take extra teacher time, but wouldn't help him move toward independence.
He can comfortably copy about 3 sentences. He can write 3 or so sentences on his own (written narration), but it's a struggle and his spelling is atrocious. He is completely ready for the creative writing part in principal, as he is very creative, but I'm not sure about the actual act of writing it down.
His math skills are fantastic. He has done TT 5 and Horizons 4 this year, so I have no concerns there. We will just continue on with Horizons.
So, Bigger, where I'm sure he will fit skill wise, and where he might even be a bit above skill wise (and which would be a repeat for the 3rd year of American history)? Or Preparing, which he might be able to stretch into, and for which he is totally ready for the concepts in the History, Bible, Storytime, Poetry boxes, but where he will struggle with reading and actual writing, at least in the beginning?
I'm afraid that if you jumped forward to Preparing Hearts that you would always be doing the independent boxes with your little sweetie for the rest of the guides. While some kiddos may need some special modifications, giving a child who struggles in certain areas plenty of time to grow into the skills can help immensely. We would never want to go too low in guide placement either, I do think that Bigger Hearts sounds like the best fit skill-wise overall and will set your child up to be more successful in the guides to come. 
). Now we just have to have the discipline to finish our current stuff before we start it! 