I mowed some switch this weekend that was frost seeded and heavy atrazine & burn down applications. It's such a wet bottom that some weeds started coming through. Just for reference, (SORRY - I SHOULD HAVE TAKEN PICS!!!!)..... It was about 12" tall, pretty small yet. That's my scenario. Stuff I drilled later, other natives, are about 6" tall. I'm sure it varies all over from one farm to another though, planting time, rain, soil, etc.
new switch.... I would have to ask "WHY" the change? Is it availability or is it that this does have advantages? Yes, CIR can have problems, disease, etc. But, so can others like Blackwell, etc. Honestly, you're likely splitting hairs. I've planted Kanlow and and another variety I can't recall and I don't think you will notice a ton of difference. All have a little different traits (Like Kanlow is taller but more spindly BUT also grows on wetter soils well too). See what the difference is or claims