There is a quadplex that I'm looking into that is across the street from a large apartment building.  The quadplex seems like an ok deal, but is the apartment going to dictate my rents and what the tenants should expect to pay for utilities?  I'm afraid that because the quadplex is a quadplex by design that it is too similar to the apartment to provide any advantages to the apartment building.

Does anyone have any insights?

If the unit makeup is similar, the apartment will affect your rental rates. Aside from that, one's residential and subject to comps like any other residential asset while the apartment is commercial and income driven for value. The quad doesn't affect the apartment much at all, in my opinion.