On my upright cabinet, I used 5/8" MDF with at least .047" of paint.  

  The 5/8" T-molding looks great.  I'm now working on a cocktail cabinet and have slightly oversized T-molding on the control panel sides.  I have't tried trimming yet, but I don't think I could make it look good.  Maybe a router with a laminate bit?  Has anyone done this?
If you use the 5/8" T-molding, I would suggest that you paint the edges the same color as the sides before installing the T-molding.  That way, you won't be able to easily see any areas that might not be fully covered.