I second the recommendation for Soundproofing Company; they are great guys. I did my room with their Speedload system and it works great.
I also second the recommendation for the AT screen. If you go too wide with a NON-AT screen, then the speakers get pushed up against the side walls which can decrease sound quality. What some have done is build columns to hide support poles, allowing them to have a 6-12" wider room. Though it of course depends on your room specifics. I would post some pics here and ask the guru's what they think. Once you lay the drywall you will never go back, so better to explore all options now.
Keep in mind RSIC-V does not damp low end frequencies as well as RSIC-1. Though if one is on a tight budget, this maybe a worthwhile trade-off, as the cost difference is significant.
I equate sound isolation to building a bridge: if your goal is to only move people across, (modest sound isolation), you only need a small, light, inexpensive bridge. If you want to move trains across, (high performance isolation), you need a bigger, more expensive bridge. It all comes back to what your goals are, and aligning them to your room and budget.
Also, don't forget to take into consideration HVAC isolation and to address wall penetrations. There is plenty of info here on these topics.