Don't know how large the 125 is, but I have a couple dead motherboards that used passive sinks on the North Bridge. Then of course you have the zalmans if you don't have a source for boards.

I just don't like the idea of increasing the physical dimensions of the esc. It's already pretty long and in my experience, the larger something is, the more of chance there is of it getting damaged.

That's true, more leverage for breakage. But it is a large angel aluminum and would protect it really. Are you talking about those heat sinks I posted?