yes it would be better but also have draw backs like weight. I would use 1in MDF on long planes like the back of the box, top of it or front side where the subs srew into. I usually do on mine 1.5in thick front and back with skeleton bracing on the inside.
it also depends greatly on the sub you plan on running. A cheap audiobahn sub will not show much bennefit in a 1in mdf over 3/4in braced properly, but if you step up to a "Super Sub" set-up then other measures will need to be taken exactly as alteraudio said.