Should you get a pneumatic stapler, the air pressure needed for the
longer staples is at least 70 psi, usually more like 100 psi is needed
when stapling into hard woods. For 1/4" staples, you might consider
setting your regulator at a lower psi for the 1/4" MDF. I've never
stapled 1/4" MDF, so I dont know how brittle it is, but it may crack/
split if you hit it with 70 or greater psi... I'm thinking thin MDF
may be somewhat as brittle as thin particle board, i.e, easy to
break. Test a scrap MDF piece before committing to your finish
project. Maybe lay the 1/4" MDF on top of a solid backing/table,
before stapling, to limit the prospect of cracking.
My rational for this is when I staple fabric onto thin face panels,
for the front face of arms of chairs, sofas, etc. Sometimes those
thin panels (cardboard, paper-type board, etc.) buckle/break under the
pressure of my normal air pressure setting (usually about 100 psi),
hence having to make new panels with a more substantial wooden board.