As I understand it, the best "short sale" offer is that without any contingencies (home inspection or mortagage) with the "down payment" not being as imporantl (although a mortage pro may more appropriately respond to this post). Typically these sales are "as is" and the bank is not likely to negoatie any home inspection issues, but if you opt to not to do inspection post contract, this ma y provide you with an out should major, costly dfects be disclosed. If u are up against other offers without the home insp contigency this may cause u to loose he property, Banks expect u to be ready, willing and able at contract signing.
The "down payment" on a short sale should coinside with your personal "buyng power", which is typically determined by your mortgage representative.
As with any offer to purchase, terms of the offer are the motivating factor (ie, days to close contigencies, resource of funds (cash v. mortgage).