If you're using MDF as the ceiling material, I'd be inclined to go with IC style cans. As this is not conditioned space, airtight is not a requirement. The only other real option is whether you intend to put the cans up first and hence can use new work cans, or you are going to put the ceiling in first and therefore need retrofit.

I've never had any issues with the cheapest (commercial electric) cans from there. Just by ones that are compatible with the trim you want to use.

Thanks. I didn't know the difference between "new" style and "retrofit" style cans until reading your response. I'll be putting the cans in after the MDF goes up so I'll use retrofits. I'm partial to using airtight cans because of insects (everything around here wants to either bite or sting you or eat your house).

Who has spec'ed MDF for a ceiling? Never heard of this. It's INCREDIBLY heavy and will delaminate and fall apart with any water.

The original ceiling material in this area was just painted sheetrock and it held up fine for 40 years. Actually I just assumed the contractor would use MDF for a good finish. We haven't actually picked the replacement material.

Revision; contractor wants to use 1/4" t&g cdx panels to enclosed it.

It would be a lot easier, at least for you, if you used new construction fixtures and let your carpenter cut holes for them. That way you don't have to deal with running cable through and already finished ceiling.