I have both Eldrazi precons from the CM sets. Should I keep them separate and upgrade them separately, or would I be better pulling the best of both to make one "really" good deck? People with both, what have you done / what's been your experience?

I have both the colorless "eldrazi" (I say it in airquotes since it kind of mostly turned out to be a colorless deck) deck and the 5 color one. Both are currently stock and unupgraded, but given my affinity for Eldrazi (and ngl, the new [[Ugin, Eye of the Storms]], I've decided I want to upgrade them.

Would I be better off combining the two decks into one "mega" Eldrazi deck, or are they better off staying separate entities? Are there at the least any particular cards I should pull from one to put in the other?