Blackjack Spreading 1-12 with $25 min bet, when to use black chips (if at all?)

Just curious your opinion on this situation. Say I’m spreading 2x$300. Would I experience more heat with 2 stacks of three blacks or 2 stacks of 12 greens? I’m just concerned on the tallness of the stack. I think the general opinion is to avoid using black chips at all costs but just wanted to confirm this.

There’s also the topic of having two color stacks. In that case, the optimal stack in my opinion would be 4 greens and 2 blacks, with the greens stacked on top of the blacks. Again, probably think most people would say stick with one color but wanted to confirm.

Source.