4198 is an extruded powder with fairly long grains. Probably not a great improvement over 3031 as far as measuring goes.
Reloder 7 is extruded, but a good deal shorter grains. My experience is that Reloder 7 is pretty easy to measure.

Reloader 7 sounds like a good option, but i'm curious as to how well TrailBoss will meter thru a rotary style powder measure. It seems to be very fluffy, not sure whether it would meter correctly. I would like to here if anybody uses TrailBoss and how well it meters out in a rotary style measure.

All Ramshot powders are fine-grained ballpowders - I really have begun liking them for my handloading. I also use a Lee powder measure, the venerable Perfect Powder Measure, and it does get hinky with long-grained extruded powders. Those I use a dipper and adjust on the beam scale by weight.

I use a lot of 3031. I have an old Redding powder measure that works great with any powder i have used with it. I do throw the charge a little light and trickle in the rest but i don't think i would really have to.