Steven, I'm not a person who likes or needs a 6 or 8 ball arsenal. Maybe it's because I'm set in my ways and/or am less versatile. If I'm bowling good, I don't like to switch balls much and can use 1 ball 90% of the time.
As you stated, the Solid was working on a wide variety of conditions, which is why I didn't chime in. But, if 1 ball isn't carrying, then the other should and vise a versa.
I guess it depends on how big of a gap between balls that you need. The pearl will go longer and snap harder than the Solid. You may want to accentuate that a bit with the layout/drilling, to spread the gap a touch.
All in all, these two balls should cover a good portion of the lane conditions, depending on the layouts, except for maybe the drier or extremely oily.
My philosophy is that there are some conditions you can't hit, because of ones style, no matter what ball you have. =:^D