Hi Bonajet,
I think you're right that you are limited to $50-100K per annum salary sacrifice into super, but 15.5% of base salary only equates to around $18K.
Super is taxed "internally" at 15%, so I guess it isn't actually tax free, but my point is that by salary sacrificing the entire amount into super it is exempt of [U]income tax[U]. I am in the process of setting up a custom fund and will then offset franking credits etc against the 15% tax, but best get your own financial advice on that one!
Cheers,
VS.