Ann - thanks so much for sharing more about your dc here!

It sounds like dd's placement is set in PHFHG - hooray!

For your ds, I am wondering about how he does not with the "creative" part of writing, but rather the "physical" part of writing? Is he able to copy, say, a paragraph each day without fatiguing? I guess when you look at the CTC plans, will he be able to do the writing part it is asking him to do? Here is a link to the CTC plans for the first week. Could you take a peek at it with just the writing parts in mind, and see if he can do those?
http://www.heartofdakota.com/pdf/CTC-First-Week.pdf
Keep in mind there is a training phase for some of these skills - about 1/3 of them are going to be tough.

Usually, 1/3 of the skills are review, 1/3 of the skills are in the semi-independent phase, and 1/3 are totally new and will take the whole year to develop.

So it's alright to think he'll need to grow into some things, like the sketching part you mentioned in Storytime. My ds's first Storytime sketch was quite small and not so helpful for him to tell his narration from, but he grew and grew in this skill until he had it down pat and did great with it by the middle of the year.

That is why that skill is part of the "T" directed box, because he'll need your help and encouragement to grow into those skills. But as far as the writing goes, I'm more concerned about him being able to do the amount of writing he is asked to do each day. If this is going to be a real struggle, and if he is going to be unable to do a good portion of it, then PHFHG would be better. I'm also more concerned if he can do the "I" boxes independently or not, as those skills he is meant to be able to have on his own.
I'm also wanting to make sure he's ready for the history reading he'll be doing independently. This is quite a level up from PHFHG's history reading he'd be doing. Here is a link to a portion of one of the harder CTC history readings he'd be having to do (the first is an excerpt from the book, and the other links are retyped but are word for word from the book):
http://www.nothingnewpress.com/guerber/ancient26-27.pdf
http://www.nothingnewpress.com/guerber/ancient-xxx.html
http://www.nothingnewpress.com/guerber/ ... xxxix.html
When you get a chance, can you share your thoughts about the writing especially, and also about the history readings? That will help me give better advice I believe.
As far as the dictation goes, if you would rather use a dictation level from PHFHG rather than CTC and are doing CTC with ds, that is just fine. Likewise, wherever he best places in R & S English is where he should start. I agree R & S English 4 sounds like a good placement, and I'd be sure to follow HOD's recommendations of doing 2/3 of it orally or on markerboard, and of only having him write around 5 -7 answers or about 1/3 of it. HTH, and I'll check back to hear your thoughts about the above things!
In Christ,
Julie