I have had 7-08's and one 284 plus a few wilcats on the 284 case. If it was me I wouldn't mess with the 284. I wouldn't hesitate picking one up if I found a screaming deal on it, but at this point would go with something else if building it myself.
If you need more than the 7-08 in a factory round I would probably run a 7 saum. Holds just as many down as a 284 in the ones I have used and as much more performance as the 284 compared to the 7-08. The wsm has a bit more speed but the saum seems to feed a bit smoother in the guns I have used.
If you want to run the wyats mag box to extend OAL on the 284, You can do the same and run a 7x57 AI and pick up nearly the case capacity of the 284 and still fit 4 down. Mine feeds great with no rail work.
