Air coolable ballast for 600w ballast absolutely necessary?

I want to get a new ballast and I've narrowed it down to two. There both switchable between MH and HPS and come with similar reflectors. The only differenence is that one of the reflectors offers a hole for the possibility of air cooling. It costs a decent bit more to order the one with air coolable capabilities.

Is it completely necessary to get the ballast with air coolable capabilites?

it depends on your enviorment i have 1 1000hps i run at night to keep room cooler it has venting hole but dont use im gonna add 1000hps then i will hook up exhaust and vent worked out 4 me 2 have vented light not knowing what i planned next