Since most cabinets I see have a slope at the top, you're probably going to have to build an entirely new back and bottom plate. So now you'll need to paint or laminate.
The only thing I would worry about is having balance. The cab you're chopping may be front-heavy, so having a wider base keeps it from tipping forward. Aside from that, I really can't think of any issues. Make sure to install cross-braces before chopping, since much of the not-folding-on-itself comes from it being a square box.
I think I would build from scratch for something like this. For a "slim" cabinet you may be able to get away with a design that utilizes only one 4x8 sheet of your choice material, and you won't have to deal with water damage or anything like that.