I'm not sure what BL-C(2)'s niche really is? It may be higher velocity and pressure .308 loads with medium to heavy projectiles? It is really too slow for the very light bullets in .223, where its efficiency is rather poor (a lot exits the bore unburned), and you can pretty much beat it by 200 fps or more with a number of faster powders. If you further ignore the SAAMI 55 kpsi pressure limit for .223, which is a throwback to the old military practice of confusing CUP with PSI, and instead use the CIP pressure limit of 62 kpsi, you'll find you can beat BL-C(2) under a 35 grain bullet by 400 fps with the right powder choice.
The military mainly uses WC 844 which is sold in canister grade as H335, but the lightest bullet they use it with is 56 grains. The lightest military bullet is the 52 grain M995 AP bullet, and that's loaded with WCR845, which has no commercial version.
IMR 4198 is really one of the best powders for accuracy loads with light bullets in .223. It doesn't meter nearly as neatly as the ball powders, but there is no point to having exact metering if the powder still doesn't produce best accuracy. Stick powder loads seem generally to be less sensitive to charge variance than spherical propellants anyway, IME.
Hatcher described National Match ammunition load development one year with two powders similar to what later became IMR 4320. One was a long, coarse stick, while the other was a short, finer grain, apparently like the modern SSC (super short cut) powders. His arsenal load equipment could only meter the coarse powder to +/- 0.85 grains. Pretty awful by handloading standards. The fine stuff would meter to a much more reasonable +/- 0.30 grains in that gear. Nonetheless, the coarse powder loads were more accurate and became that year's NM ammunition and several records were set with it. Hatcher credited that to the superior ignition properties of the coarse sticks. The larger spaces between the grains allow the flame front to move better.
I think there is more to it than ignition sensitivity. Many match shooters have found IMR 4064 to produce more consistently accurate ammunition than IMR 4895 in the .30 caliber guns. John Feamster published a chart showing the ammunts of each required to produce the same velocities in .308 ammunition with 168 grain SMK bullets. Curiously, the required charge weights crossed over at about 2400 fps. Below that it took less charge weight of IMR 4064 to reach 2200 fps or 2300 fps. Since both powders are single-base propellants with the same energy content per pound, that smaller amount indicated the IMR 4064 was the faster powder. At 2400 fps, though, the charge weight is about the same. At 2500 fps it took less IMR 4895, indicating the IMR 4064 was slower at the pressure needed to produce that velocity. So the IMR 4064 seems to respond to increased pressure with less burn rate increase than IMR 4895 does. That makes it more immune to charge weight variance and should make it less sensitive to temperature as well.
Anyway, the bottom line is that the best powder choice can't necessarily be determined by published burn rate (they can change order with pressure, as in Feamster's example) or metering ease or case fill or any other single factor you might dream up to measure. You still end up having to try a passel of powders to find the best one for your gun and bullets.
For the .30-06, the listed loads on the Hodgdon site fill the case poorly, so a fair amount of MV variance is likely. I would work up to them using a magnum primer for that reason, as that should tend to reduce MV variance by providing higher start pressure. My .30-06's seem to like Varget best for accuracy loads.