Have you measured the pause times of free()? Because they are not deterministic, and I have met few people who understand in detail how complex it can be in practice. In the limit, free() can be as bad as GC pause times because of chained deallocation--i.e. not statically bounded.
In practice, almost all real-time systems use this strategy, even going so far as to allocate all memory at compile time. The first versions of Virgil (I and II) used this strategy and compiled to C.
When doing this, the whole debate of memory safe (automatic) vs unsafe (manual) is completely orthogonal.
