That depends what the aim is. It seems to me that the aim of FFP as it currently stands is to encourage good financial management (i.e. solvency), and discourage dependency upon either loans or gifts from chairmen. It's clearly NOT aimed at encouraging a level playing field. However the kind of system I proposed above (an absolute limit) does the latter at the expense of the former; so you end up with a competitive league, but not necessarily good financial management/solvency.
Manchester City are the least insolvent club of the 92, yet they are subject to FFP sanctions.