Hi Cindy!

I'm not sure if this will help in your decision or not, but here is a thread where Carrie explains the pacing of R & S English that may be helpful:
viewtopic.php?f=6&t=5494
If you get R & S English 6 and find it to be too much, you can return it within 30 days and just order the other one. Or, you could just keep it (as you'll be using it later anyway), and get R & S English 5 at that point. In the description of R & S English 6 there is this note to consider:
Older students who have not had significant grammar instruction should begin with English 4 or 5. Older students who have had a very rigorous background in grammar can begin in Level 6. Since this is an advanced course, we recommend that students complete English 6 by the end of grade 8 in preparation for high school language arts.
I hope something here helps as you ponder this. R & S English is an outstanding grammar (and writing) program! I think you will be very pleased with it. You may have already read that HOD recommends doing a good portion of it orally, but in case not, here is a link to how we've enjoyed going about doing this in our home:
viewtopic.php?f=6&t=4659&p=34269#p34269
In Christ,
Julie