I think the original question was about the funds transfer tax. Taxation of your rental income is another thing. So whatever you do the taxman will have his share. You do save a lot of money, though, by operating with a real estate investment company. Long-term planning is essential here.
The usual transfer tax is 8% but when you buy for an SL the rate is 2%. This is, however, not meant to apply to your own residence but rather to rentals. The SL has to be a specifically real estate investment company. Talk to a lawyer before you jump into this.