As it was noted repeatedly, SPSTM experiments are facing numerous technical difficulties, many of which were identified at the prototype stage16 and by various experimental groups17,20,23,24:
None of the above problems, however, appear insurmountable at this point: alternative tip materials can fight the magnetic effects; faster and smaller STM's will help with drift; dealing with noises is every experimentalist's headache, but it never stopped anybody anyway; even the test system problem may be solved by stepped surfaces, for example. There is certainly room for future developments, but the situation is far from desperate.
In addition, there are a few other alternative SPSTM techniques, such as idea of Alvarado et al. to combine the SEMPA6 technique and polarized fluorescence into STM-induced fluorescence with polarization analysis25. These ideas are generally only on very preliminary stages right now, but so were the current favorites just a few years ago, and only the future will tell us which one them will be the first to reach the ultimate goal of magnetic microscopy with atomic resolution.