If its a decent quality one it shouldnt matter. The constant speed thing dosen't matter because at the point when your clutch fan is spinning fastest, youre going pretty fast...at high speeds there is enough airflow just from speed to cool the radiator fine with no fan. The fan is only important at low speeds, and the elec fans have more than enough cfm for low speed. As long as you use a known quality brand then you should be fine.
