Re: 223wssm and243wssm
As a high volume varmint cartridge, they may prove to be too much of a good thing. Barrel life with cartridges like 22/250 and 220 swift is short enough without stuffing more powder down the bore. The extra vel still does not make up for low BC bullets. I doubt they will increase the range or wind bucking significantly. I guess Ian will give us more insight soon.
Where they are really interesting is the bases for LR cartridges in 6mm, and 6.5. Personally, I would look at an improved version of the 243WSSM for a 6.5 or 7mm 1km BR cartridge. The case capacity is perfect and the short fat case may lead to some accuracy benefits. Would make a close competitor with the 6.5-284. With a longer neck, the WSSM could have better throat life.
If left in the 243 state, I would definitely look at 105 to 115gr type bullets, slow twist and a min. 26" barrel. Now we can push these bullets to 3200fps without scary pressures. Wonder if the bullets will stay together? Any 6-284 shooters out there with info?