I am not concerned about the cleaning aspects of the radius rifling, I have owned square bottom grooves in the past and I think they clean about the same as well. I was more concerned if there was any problem squeezing a thick patch into a small bore with a tiny ball. I was wondering if a square groove would allow a thinner patch and still perform as well. Maybe I'm making mountains out of molehillls.
About 1974 I bought a Dixie Gunworks Rifle, Made in Belgium. My introduction to ML. Aside from lock problems as it aged, it was always very accurate. It had square bottom groves, and never had a problem cleaning it and never had a problem with rust in the bore. Shot it with relatively thin patches (never actually measured thickness, but I guess around .010) and could thumb start every round. TC uses square grooves, I don't own one but they seem to shoot very accurately. Was radius rifling created to produce a more historically accurate rifle barrel or was it done to facilitate cleaning, or are they supposed to be more accurate, don't know. I'm getting a little off topic.